Update changelog for 3.1.0 beta1 (#353)

Signed-off-by: James Hillyerd <james@hillyerd.com>

.envrc

@@ -0,0 +1 @@
+use nix

.github/workflows/build-and-test.yml

@@ -6,14 +6,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.17', '1.16' ]
+        go: [ '1.20', '1.19' ]
     name: Go ${{ matrix.go }} build
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
       - name: Setup Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
           go-version: ${{ matrix.go }}
       - name: Build and test

.github/workflows/docker-build.yml

@@ -9,10 +9,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Docker meta
         id: meta
-        uses: docker/metadata-action@v3
+        uses: docker/metadata-action@v4
         with:
           images: |
             inbucket/inbucket
@@ -25,25 +25,30 @@ jobs:
             type=edge,branch=main
           flavor: |
             latest=auto
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+        with:
+          platforms: all
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v1
+        uses: docker/setup-buildx-action@v2
       - name: Login to DockerHub
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@v1
+        uses: docker/login-action@v2
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Login to GitHub Container Registry
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@v1
+        uses: docker/login-action@v2
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Build and push
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v4
         with:
           context: .
+          platforms: linux/amd64,linux/arm64, linux/arm/v7
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}

.github/workflows/release.yml

@@ -8,34 +8,32 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
       - name: Setup Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
-          go-version: 1.17
+          go-version: 1.19
       - name: Setup Node.js
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v3
         with:
-          node-version: '14.x'
+          node-version: '16.x'
-      - name: Setup Elm
+          cache: 'yarn'
-        uses: jorelali/setup-elm@v2
+          cache-dependency-path: ui/yarn.lock
-        with:
-          elm-version: 0.19.1
       - name: Build frontend
         run: |
-          npm ci
+          yarn install --frozen-lockfile --non-interactive
-          npm run build
+          yarn run build
         working-directory: ./ui
       - name: Test build release
-        uses: goreleaser/goreleaser-action@v2
+        uses: goreleaser/goreleaser-action@v4
         if: "!startsWith(github.ref, 'refs/tags/v')"
         with:
           version: latest
           args: release --snapshot
       - name: Build and publish release
-        uses: goreleaser/goreleaser-action@v2
+        uses: goreleaser/goreleaser-action@v4
         if: "startsWith(github.ref, 'refs/tags/v')"
         with:
           version: latest

.gitignore

@@ -30,6 +30,8 @@ tags.*
 # Desktop Services Store on macOS
 .DS_Store
 
+/.direnv
+
 # Inbucket binaries
 /client
 /client.exe
@@ -52,3 +54,7 @@ repl-temp-*
 /ui/dist/
 # Dependency directories
 /ui/node_modules
+/ui/.parcel-cache
+
+# Test lua files
+/inbucket.lua

.goreleaser.yml

@@ -48,10 +48,9 @@ builds:
 
 archives:
   - id: tarball
+    rlcp: true
     format: tar.gz
     wrap_in_directory: true
-    name_template: '{{ .Binary }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}{{ if .Arm }}v{{
-      .Arm }}{{ end }}'
     format_overrides:
       - goos: windows
         format: zip

CHANGELOG.md

@@ -4,7 +4,42 @@ Change Log
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
-## [Unreleased]
+## [v3.1.0-beta1] - 2023-02-28
+
+### Added
+- Monitor tab updates when messages are deleted (#337)
+- Initial framework for extensions
+- Initial Lua scripting implementation, supporting events:
+  - after.message_deleted
+  - after.message_stored
+  - before.mail_accepted
+- Provide `http` and `json` modules for Lua scripts
+
+### Fixed
+- Support for IP address as domain in RCPT TO (#285)
+
+
+## [v3.0.4] - 2022-10-02
+
+### Fixed
+- More flexible support of `AUTH=<>` FROM parameter (#291)
+
+
+## [v3.0.3] - 2022-08-07
+
+### Fixed
+- Support for `AUTH=<>` FROM parameter (#284)
+
+
+## [v3.0.2] - 2022-07-04
+
+Note: We had to abandon the 3.0.1 release, see the blog post [What happened to
+3.0?](https://www.inbucket.org/news/2022/05/whathappenedtothree.html) for
+details.
+
+### Changed
+- arm Docker builds now rely on amd64 frontend build stage
+- Frontend build migrated from npm+webpack to yarn+parcel, node 16
 
 
 ## [v3.0.1-rc2] - 2022-01-23
@@ -293,10 +328,14 @@ No change from beta1.
   specific message.
 
 
-[Unreleased]:   https://github.com/inbucket/inbucket/compare/v3.0.1-rc2...main
+[Unreleased]:   https://github.com/inbucket/inbucket/compare/v3.1.0-beta1...main
+[v3.1.0-beta1]: https://github.com/inbucket/inbucket/compare/v3.0.4...v3.1.0-beta1
+[v3.0.4]:       https://github.com/inbucket/inbucket/compare/v3.0.3...v3.0.4
+[v3.0.3]:       https://github.com/inbucket/inbucket/compare/v3.0.2...v3.0.3
+[v3.0.2]:       https://github.com/inbucket/inbucket/compare/v3.0.1-rc2...v3.0.2
 [v3.0.1-rc2]:   https://github.com/inbucket/inbucket/compare/v3.0.1-rc1...v3.0.1-rc2
 [v3.0.1-rc1]:   https://github.com/inbucket/inbucket/compare/v3.0.0...v3.0.1-rc1
-[v3.0.0]:   https://github.com/inbucket/inbucket/compare/v3.0.0-rc4...v3.0.0
+[v3.0.0]:       https://github.com/inbucket/inbucket/compare/v3.0.0-rc4...v3.0.0
 [v3.0.0-rc4]:   https://github.com/inbucket/inbucket/compare/v3.0.0-rc2...v3.0.0-rc4
 [v3.0.0-rc2]:   https://github.com/inbucket/inbucket/compare/v3.0.0-rc1...v3.0.0-rc2
 [v3.0.0-rc1]:   https://github.com/inbucket/inbucket/compare/v3.0.0-beta3...v3.0.0-rc1

Dockerfile

@@ -1,35 +1,33 @@
 # Docker build file for Inbucket: https://www.inbucket.org/
 
-# Install build-time dependencies
+### Build frontend
-FROM golang:1.17-alpine3.14 as builder
+# Due to no official elm compiler for arm; build frontend with amd64.
-RUN apk add --no-cache --virtual .build-deps g++ git make npm python3
+FROM --platform=linux/amd64 node:16 as frontend
+WORKDIR /build
+COPY . .
+WORKDIR /build/ui
+RUN rm -rf .parcel-cache dist elm-stuff node_modules
+RUN yarn install --frozen-lockfile --non-interactive
+RUN yarn run build
+
+### Build backend
+FROM golang:1.19-alpine3.17 as backend
+RUN apk add --no-cache --virtual .build-deps g++ git make
 WORKDIR /build
 COPY . .
 ENV CGO_ENABLED 0
 RUN make clean deps
-WORKDIR /build/ui
-RUN rm -rf dist elm-stuff node_modules
-RUN npm ci
-ADD https://github.com/elm/compiler/releases/download/0.19.1/binary-for-linux-64-bit.gz elm.gz
-RUN gunzip elm.gz && chmod 755 elm && mv elm /usr/bin/
-
-# Build server
-WORKDIR /build
 RUN go build -o inbucket \
   -ldflags "-X 'main.version=$(git describe --tags --always)' -X 'main.date=$(date -Iseconds)'" \
   -v ./cmd/inbucket
 
-# Build frontend
+### Run in minimal image
-WORKDIR /build/ui
+FROM alpine:3.17
-RUN npm run build
-
-# Run in minimal image
-FROM alpine:3.14
 RUN apk --no-cache add tzdata
 WORKDIR /opt/inbucket
 RUN mkdir bin defaults ui
-COPY --from=builder /build/inbucket bin
+COPY --from=backend /build/inbucket bin
-COPY --from=builder /build/ui/dist ui
+COPY --from=frontend /build/ui/dist ui
 COPY etc/docker/defaults/greeting.html defaults
 COPY etc/docker/defaults/start-inbucket.sh /
 

Makefile

@@ -9,7 +9,7 @@ commands = client inbucket
 
 all: clean test lint build
 
-$(commands): %: cmd/%
+$(commands): %: cmd/% $(SRC)
 	go build ./$<
 
 clean:

README.md

@@ -33,14 +33,13 @@ tracks our tagged releases, and `edge` tracks our potentially unstable
 
 ## Building from Source
 
-You will need functioning [Go], [Elm] and [Node.js] installations for this to
+You will need functioning [Go] and [Node.js] installations for this to work.
-work.
 
 ```sh
 git clone https://github.com/inbucket/inbucket.git
 cd inbucket/ui
-npm ci
+yarn install
-npm run build
+yarn build
 cd ..
 go build ./cmd/inbucket
 ```

cmd/inbucket/main.go

@@ -15,18 +15,10 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
-	"github.com/inbucket/inbucket/pkg/message"
+	"github.com/inbucket/inbucket/pkg/server"
-	"github.com/inbucket/inbucket/pkg/msghub"
-	"github.com/inbucket/inbucket/pkg/policy"
-	"github.com/inbucket/inbucket/pkg/rest"
-	"github.com/inbucket/inbucket/pkg/server/pop3"
-	"github.com/inbucket/inbucket/pkg/server/smtp"
-	"github.com/inbucket/inbucket/pkg/server/web"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/storage/file"
 	"github.com/inbucket/inbucket/pkg/storage/mem"
-	"github.com/inbucket/inbucket/pkg/stringutil"
-	"github.com/inbucket/inbucket/pkg/webui"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 )
@@ -114,36 +106,16 @@ func main() {
 		}
 	}
 
-	// Configure internal services.
+	// Configure and start internal services.
-	rootCtx, rootCancel := context.WithCancel(context.Background())
+	svcCtx, svcCancel := context.WithCancel(context.Background())
-	shutdownChan := make(chan bool)
+	services, err := server.FullAssembly(conf)
-	store, err := storage.FromConfig(conf.Storage)
 	if err != nil {
+		startupLog.Fatal().Err(err).Msg("Fatal error during startup")
 		removePIDFile(*pidfile)
-		startupLog.Fatal().Err(err).Str("module", "storage").Msg("Fatal storage error")
 	}
-	msgHub := msghub.New(rootCtx, conf.Web.MonitorHistory)
+	services.Start(svcCtx, func() {
-	addrPolicy := &policy.Addressing{Config: conf}
+		startupLog.Debug().Msg("All services report ready")
-	mmanager := &message.StoreManager{AddrPolicy: addrPolicy, Store: store, Hub: msgHub}
+	})
-
-	// Start Retention scanner.
-	retentionScanner := storage.NewRetentionScanner(conf.Storage, store, shutdownChan)
-	retentionScanner.Start()
-
-	// Configure routes and start HTTP server.
-	prefix := stringutil.MakePathPrefixer(conf.Web.BasePath)
-	webui.SetupRoutes(web.Router.PathPrefix(prefix("/serve/")).Subrouter())
-	rest.SetupRoutes(web.Router.PathPrefix(prefix("/api/")).Subrouter())
-	web.Initialize(conf, shutdownChan, mmanager, msgHub)
-	go web.Start(rootCtx)
-
-	// Start POP3 server.
-	pop3Server := pop3.New(conf.POP3, shutdownChan, store)
-	go pop3Server.Start(rootCtx)
-
-	// Start SMTP server.
-	smtpServer := smtp.NewServer(conf.SMTP, shutdownChan, mmanager, addrPolicy)
-	go smtpServer.Start(rootCtx)
 
 	// Loop forever waiting for signals or shutdown channel.
 signalLoop:
@@ -155,24 +127,31 @@ signalLoop:
 				// Shutdown requested
 				log.Info().Str("phase", "shutdown").Str("signal", "SIGINT").
 					Msg("Received SIGINT, shutting down")
-				close(shutdownChan)
+				svcCancel()
+				break signalLoop
 			case syscall.SIGTERM:
 				// Shutdown requested
 				log.Info().Str("phase", "shutdown").Str("signal", "SIGTERM").
 					Msg("Received SIGTERM, shutting down")
-				close(shutdownChan)
+				svcCancel()
+				break signalLoop
 			}
-		case <-shutdownChan:
+		case <-services.Notify():
-			rootCancel()
+			log.Info().Str("phase", "shutdown").Msg("Shutting down due to service failure")
+			svcCancel()
 			break signalLoop
 		}
 	}
 
 	// Wait for active connections to finish.
 	go timedExit(*pidfile)
-	smtpServer.Drain()
+	log.Debug().Str("phase", "shutdown").Msg("Draining SMTP connections")
-	pop3Server.Drain()
+	services.SMTPServer.Drain()
-	retentionScanner.Join()
+	log.Debug().Str("phase", "shutdown").Msg("Draining POP3 connections")
+	services.POP3Server.Drain()
+	log.Debug().Str("phase", "shutdown").Msg("Checking retention scanner is stopped")
+	services.RetentionScanner.Join()
+
 	removePIDFile(*pidfile)
 	closeLog()
 }

doc/config.md

@@ -9,7 +9,8 @@ variables it supports:
 
     KEY                                 DEFAULT             DESCRIPTION
     INBUCKET_LOGLEVEL                   info                debug, info, warn, or error
-    INBUCKET_MAILBOXNAMING              local               Use local or full addressing
+    INBUCKET_LUA_PATH                   inbucket.lua        Lua script path
+    INBUCKET_MAILBOXNAMING              local               Use local, full, or domain addressing
     INBUCKET_SMTP_ADDR                  0.0.0.0:2500        SMTP server IP4 host:port
     INBUCKET_SMTP_DOMAIN                inbucket            HELO domain
     INBUCKET_SMTP_MAXRECIPIENTS         200                 Maximum RCPT TO per message
@@ -56,6 +57,16 @@ off with `warn` or `error`.
 - Default: `info`
 - Values: one of `debug`, `info`, `warn`, or `error`
 
+### Lua Script
+
+`INBUCKET_LUA_PATH`
+
+This is the path to the (optional) Inbucket Lua script.  If the specified file
+is present, Inbucket will load it during startup.  Ignored if the file is not
+found, or the setting is empty.
+
+- Default: `inbucket.lua`
+
 ### Mailbox Naming
 
 `INBUCKET_MAILBOXNAMING`

etc/dev-start.sh

@@ -3,6 +3,7 @@
 # description: Developer friendly Inbucket configuration
 
 export INBUCKET_LOGLEVEL="debug"
+#export INBUCKET_MAILBOXNAMING="domain"
 export INBUCKET_SMTP_REJECTDOMAINS="bad-actors.local"
 #export INBUCKET_SMTP_DEFAULTACCEPT="false"
 export INBUCKET_SMTP_ACCEPTDOMAINS="good-actors.local"

etc/docker/docker-run.sh

@@ -3,7 +3,7 @@
 # description: Launch Inbucket's docker image
 
 # Docker Image Tag
-IMAGE="inbucket/inbucket"
+IMAGE="inbucket/inbucket:edge"
 
 # Ports exposed on host:
 PORT_HTTP=9000

etc/rest-apiv1.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # rest-apiv1.sh
 # description: Script to access Inbucket REST API version 1
 

etc/swaks-tests/run-tests.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # run-tests.sh
 # description: Generate test emails for Inbucket
 
@@ -24,7 +24,7 @@ case "$1" in
     ;;
 esac
 
-export SWAKS_OPT_server="127.0.0.1:2500"
+export SWAKS_OPT_server="${SWAKS_OPT_server:-127.0.0.1:2500}"
 export SWAKS_OPT_to="$to@inbucket.local"
 
 # Basic test
@@ -59,3 +59,7 @@ swaks $* --data nonmime-html-inlined.raw
 
 # Incorrect charset, malformed final boundary
 swaks $* --data mime-errors.raw
+
+# IP RCPT domain
+swaks $* --to="swaks@[127.0.0.1]" --h-Subject: "IPv4 RCPT Address" --body text.txt
+swaks $* --to="swaks@[IPv6:2001:db8:aaaa:1::100]" --h-Subject: "IPv6 RCPT Address" --body text.txt

go.mod

@@ -1,23 +1,42 @@
 module github.com/inbucket/inbucket
 
 require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/cjoudrey/gluahttp v0.0.0-20201111170219-25003d9adfa9
-	github.com/gogs/chardet v0.0.0-20211120154057-b7413eaefb8f // indirect
 	github.com/google/subcommands v1.2.0
 	github.com/gorilla/css v1.0.0
 	github.com/gorilla/mux v1.8.0
-	github.com/gorilla/websocket v1.4.2
+	github.com/gorilla/websocket v1.5.0
-	github.com/jaytaylor/html2text v0.0.0-20211105163654-bc68cce691ba // indirect
+	github.com/inbucket/gopher-json v0.2.0
-	github.com/jhillyerd/enmime v0.9.2
+	github.com/jhillyerd/enmime v0.11.0
 	github.com/jhillyerd/goldiff v0.1.0
 	github.com/kelseyhightower/envconfig v1.4.0
-	github.com/mattn/go-runewidth v0.0.13 // indirect
+	github.com/microcosm-cc/bluemonday v1.0.22
-	github.com/microcosm-cc/bluemonday v1.0.17
+	github.com/rs/zerolog v1.29.0
-	github.com/rs/zerolog v1.26.1
+	github.com/stretchr/testify v1.8.2
-	github.com/stretchr/testify v1.7.0
+	github.com/yuin/gopher-lua v1.1.0
-	golang.org/x/net v0.0.0-20220114011407-0dd24b26b47d
+	golang.org/x/net v0.7.0
-	golang.org/x/text v0.3.7 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )
 
-go 1.13
+require (
+	github.com/aymerick/douceur v0.2.0 // indirect
+	github.com/cention-sany/utf7 v0.0.0-20170124080048-26cad61bd60a // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-test/deep v1.1.0 // indirect
+	github.com/gogs/chardet v0.0.0-20211120154057-b7413eaefb8f // indirect
+	github.com/jaytaylor/html2text v0.0.0-20211105163654-bc68cce691ba // indirect
+	github.com/kr/pretty v0.3.1 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.17 // indirect
+	github.com/mattn/go-runewidth v0.0.14 // indirect
+	github.com/olekukonko/tablewriter v0.0.5 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rivo/uniseg v0.4.4 // indirect
+	github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf // indirect
+	golang.org/x/sys v0.5.0 // indirect
+	golang.org/x/text v0.7.0 // indirect
+	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+go 1.18

go.sum

@@ -2,12 +2,16 @@ github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuP
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
 github.com/cention-sany/utf7 v0.0.0-20170124080048-26cad61bd60a h1:MISbI8sU/PSK/ztvmWKFcI7UGb5/HQT7B+i3a2myKgI=
 github.com/cention-sany/utf7 v0.0.0-20170124080048-26cad61bd60a/go.mod h1:2GxOXOlEPAMFPfp014mK1SWq8G8BN8o7/dfYqJrVGn8=
-github.com/coreos/go-systemd/v22 v22.3.2/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/cjoudrey/gluahttp v0.0.0-20201111170219-25003d9adfa9 h1:rdWOzitWlNYeUsXmz+IQfa9NkGEq3gA/qQ3mOEqBU6o=
+github.com/cjoudrey/gluahttp v0.0.0-20201111170219-25003d9adfa9/go.mod h1:X97UjDTXp+7bayQSFZk2hPvCTmTZIicUjZQRtkwgAKY=
+github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-test/deep v1.0.7 h1:/VSMRlnY/JSyqxQUzQLKVMAskpY/NZKFA5j2P+0pP2M=
 github.com/go-test/deep v1.0.7/go.mod h1:QV8Hv/iy04NyLBxAdO9njL0iVPN1S4d/A3NVv1V36o8=
+github.com/go-test/deep v1.1.0 h1:WOcxcdHcvdgThNXjw0t76K42FXTU7HpNQWHpA2HHNlg=
+github.com/go-test/deep v1.1.0/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
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-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

pkg/config/config.go

@@ -58,14 +58,20 @@ func (n *mbNaming) Decode(v string) error {
 
 // Root contains global configuration, and structs with for specific sub-systems.
 type Root struct {
-	LogLevel      string   `required:"true" default:"info" desc:"debug, info, warn, or error"`
+	LogLevel      string `required:"true" default:"info" desc:"debug, info, warn, or error"`
-	MailboxNaming mbNaming `required:"true" default:"local" desc:"Use local, full or domain addressing"`
+	Lua           Lua
+	MailboxNaming mbNaming `required:"true" default:"local" desc:"Use local, full, or domain addressing"`
 	SMTP          SMTP
 	POP3          POP3
 	Web           Web
 	Storage       Storage
 }
 
+// Lua contains the Lua extension host configuration.
+type Lua struct {
+	Path string `required:"false" default:"inbucket.lua" desc:"Lua script path"`
+}
+
 // SMTP contains the SMTP server configuration.
 type SMTP struct {
 	Addr            string        `required:"true" default:"0.0.0.0:2500" desc:"SMTP server IP4 host:port"`

pkg/extension/async_broker.go

@@ -0,0 +1,89 @@
+package extension
+
+import (
+	"errors"
+	"sync"
+	"time"
+)
+
+// AsyncEventBroker maintains a list of listeners interested in a specific type
+// of event.  Events are sent in parallel to all listeners, and no result is
+// returned.
+type AsyncEventBroker[E any] struct {
+	sync.RWMutex
+	listenerNames []string  // Ordered listener names.
+	listenerFuncs []func(E) // Ordered listener functions.
+}
+
+// Emit sends the provided event to each registered listener in parallel.
+func (eb *AsyncEventBroker[E]) Emit(event *E) {
+	eb.RLock()
+	defer eb.RUnlock()
+
+	for _, l := range eb.listenerFuncs {
+		// Events are copied to minimize the risk of mutation.
+		go l(*event)
+	}
+}
+
+// AddListener registers the named listener, replacing one with a duplicate
+// name if present.  Listeners should be added in order of priority, most
+// significant first.
+func (eb *AsyncEventBroker[E]) AddListener(name string, listener func(E)) {
+	eb.Lock()
+	defer eb.Unlock()
+
+	eb.lockedRemoveListener(name)
+	eb.listenerNames = append(eb.listenerNames, name)
+	eb.listenerFuncs = append(eb.listenerFuncs, listener)
+}
+
+// RemoveListener unregisters the named listener.
+func (eb *AsyncEventBroker[E]) RemoveListener(name string) {
+	eb.Lock()
+	defer eb.Unlock()
+
+	eb.lockedRemoveListener(name)
+}
+
+func (eb *AsyncEventBroker[E]) lockedRemoveListener(name string) {
+	for i, entry := range eb.listenerNames {
+		if entry == name {
+			eb.listenerNames = append(eb.listenerNames[:i], eb.listenerNames[i+1:]...)
+			eb.listenerFuncs = append(eb.listenerFuncs[:i], eb.listenerFuncs[i+1:]...)
+			break
+		}
+	}
+}
+
+// AsyncTestListener returns a func that will wait for an event and return it, or timeout
+// with an error.
+func (eb *AsyncEventBroker[E]) AsyncTestListener(name string, capacity int) func() (*E, error) {
+	// Send event down channel.
+	events := make(chan E, capacity)
+	eb.AddListener(name,
+		func(msg E) {
+			events <- msg
+		})
+
+	count := 0
+
+	return func() (*E, error) {
+		count++
+
+		defer func() {
+			if count >= capacity {
+				eb.RemoveListener(name)
+				close(events)
+			}
+		}()
+
+		select {
+		case event := <-events:
+			return &event, nil
+
+		case <-time.After(time.Second * 2):
+			return nil, errors.New("Timeout waiting for event")
+		}
+	}
+}

pkg/extension/async_broker_test.go

@@ -0,0 +1,101 @@
+package extension_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// Simple smoke test without using AsyncTestListener.
+func TestAsyncBrokerEmitCallsOneListener(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listener.
+	events := make(chan string, 1)
+	listener := func(s string) {
+		events <- s
+	}
+	broker.AddListener("x", listener)
+
+	want := "bacon"
+	broker.Emit(&want)
+
+	var got string
+	select {
+	case event := <-events:
+		got = event
+
+	case <-time.After(time.Second * 2):
+		t.Fatal("Timeout waiting for event")
+	}
+
+	if got != want {
+		t.Errorf("Emit got %q, want %q", got, want)
+	}
+}
+
+func TestAsyncBrokerEmitCallsMultipleListeners(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("first", 1)
+	second := broker.AsyncTestListener("second", 1)
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.NoError(t, err)
+	assert.Equal(t, want, *first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerAddingDuplicateNameReplacesPrevious(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("dup", 1)
+	second := broker.AsyncTestListener("dup", 1)
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.Error(t, err)
+	assert.Nil(t, first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerRemovingListenerSuccessful(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("1", 1)
+	second := broker.AsyncTestListener("2", 1)
+	broker.RemoveListener("1")
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.Error(t, err)
+	assert.Nil(t, first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerRemovingMissingListener(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+	broker.RemoveListener("doesn't crash")
+}

pkg/extension/broker.go

@@ -0,0 +1,59 @@
+package extension
+
+import (
+	"sync"
+)
+
+// EventBroker maintains a list of listeners interested in a specific type
+// of event.
+type EventBroker[E any, R comparable] struct {
+	sync.RWMutex
+	listenerNames []string     // Ordered listener names.
+	listenerFuncs []func(E) *R // Ordered listener functions.
+}
+
+// Emit sends the provided event to each registered listener in order, until
+// one returns a non-nil result.  That result will be returned to the caller.
+func (eb *EventBroker[E, R]) Emit(event *E) *R {
+	eb.RLock()
+	defer eb.RUnlock()
+
+	for _, l := range eb.listenerFuncs {
+		// Events are copied to minimize the risk of mutation.
+		if result := l(*event); result != nil {
+			return result
+		}
+	}
+
+	return nil
+}
+
+// AddListener registers the named listener, replacing one with a duplicate
+// name if present.  Listeners should be added in order of priority, most
+// significant first.
+func (eb *EventBroker[E, R]) AddListener(name string, listener func(E) *R) {
+	eb.Lock()
+	defer eb.Unlock()
+
+	eb.lockedRemoveListener(name)
+	eb.listenerNames = append(eb.listenerNames, name)
+	eb.listenerFuncs = append(eb.listenerFuncs, listener)
+}
+
+// RemoveListener unregisters the named listener.
+func (eb *EventBroker[E, R]) RemoveListener(name string) {
+	eb.Lock()
+	defer eb.Unlock()
+
+	eb.lockedRemoveListener(name)
+}
+
+func (eb *EventBroker[E, R]) lockedRemoveListener(name string) {
+	for i, entry := range eb.listenerNames {
+		if entry == name {
+			eb.listenerNames = append(eb.listenerNames[:i], eb.listenerNames[i+1:]...)
+			eb.listenerFuncs = append(eb.listenerFuncs[:i], eb.listenerFuncs[i+1:]...)
+			break
+		}
+	}
+}

pkg/extension/broker_test.go

@@ -0,0 +1,134 @@
+package extension_test
+
+import (
+	"testing"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+)
+
+func TestBrokerEmitCallsOneListener(t *testing.T) {
+	broker := &extension.EventBroker[string, bool]{}
+
+	// Setup listener.
+	var got string
+	listener := func(s string) *bool {
+		got = s
+		return nil
+	}
+	broker.AddListener("x", listener)
+
+	want := "bacon"
+	broker.Emit(&want)
+	if got != want {
+		t.Errorf("Emit got %q, want %q", got, want)
+	}
+}
+
+func TestBrokerEmitCallsMultipleListeners(t *testing.T) {
+	broker := &extension.EventBroker[string, bool]{}
+
+	// Setup listeners.
+	var first_got, second_got string
+	first := func(s string) *bool {
+		first_got = s
+		return nil
+	}
+	second := func(s string) *bool {
+		second_got = s
+		return nil
+	}
+
+	broker.AddListener("1", first)
+	broker.AddListener("2", second)
+
+	want := "hi"
+	broker.Emit(&want)
+	if first_got != want {
+		t.Errorf("first got %q, want %q", first_got, want)
+	}
+	if second_got != want {
+		t.Errorf("second got %q, want %q", second_got, want)
+	}
+}
+
+func TestBrokerEmitCapturesFirstResult(t *testing.T) {
+	broker := &extension.EventBroker[struct{}, string]{}
+
+	// Setup listeners.
+	makeListener := func(result *string) func(struct{}) *string {
+		return func(s struct{}) *string { return result }
+	}
+	first := "first"
+	second := "second"
+	broker.AddListener("0", makeListener(nil))
+	broker.AddListener("1", makeListener(&first))
+	broker.AddListener("2", makeListener(&second))
+
+	want := first
+	got := broker.Emit(&struct{}{})
+	if got == nil {
+		t.Errorf("Emit got nil, want %q", want)
+	} else if *got != want {
+		t.Errorf("Emit got %q, want %q", *got, want)
+	}
+}
+
+func TestBrokerAddingDuplicateNameReplacesPrevious(t *testing.T) {
+	broker := &extension.EventBroker[string, bool]{}
+
+	// Setup listeners.
+	var first_got, second_got string
+	first := func(s string) *bool {
+		first_got = s
+		return nil
+	}
+	second := func(s string) *bool {
+		second_got = s
+		return nil
+	}
+
+	broker.AddListener("dup", first)
+	broker.AddListener("dup", second)
+
+	want := "hi"
+	broker.Emit(&want)
+	if first_got != "" {
+		t.Errorf("first got %q, want empty string", first_got)
+	}
+	if second_got != want {
+		t.Errorf("second got %q, want %q", second_got, want)
+	}
+}
+
+func TestBrokerRemovingListenerSuccessful(t *testing.T) {
+	broker := &extension.EventBroker[string, bool]{}
+
+	// Setup listeners.
+	var first_got, second_got string
+	first := func(s string) *bool {
+		first_got = s
+		return nil
+	}
+	second := func(s string) *bool {
+		second_got = s
+		return nil
+	}
+
+	broker.AddListener("1", first)
+	broker.AddListener("2", second)
+	broker.RemoveListener("1")
+
+	want := "hi"
+	broker.Emit(&want)
+	if first_got != "" {
+		t.Errorf("first got %q, want empty string", first_got)
+	}
+	if second_got != want {
+		t.Errorf("second got %q, want %q", second_got, want)
+	}
+}
+
+func TestBrokerRemovingMissingListener(t *testing.T) {
+	broker := &extension.EventBroker[string, bool]{}
+	broker.RemoveListener("doesn't crash")
+}

pkg/extension/event/events.go

@@ -0,0 +1,24 @@
+package event
+
+import (
+	"net/mail"
+	"time"
+)
+
+// AddressParts contains the local and domain parts of an email address.
+type AddressParts struct {
+	Local  string
+	Domain string
+}
+
+// MessageMetadata contains the basic header data for a message event.
+type MessageMetadata struct {
+	Mailbox string
+	ID      string
+	From    *mail.Address
+	To      []*mail.Address
+	Date    time.Time
+	Subject string
+	Size    int64
+	Seen    bool
+}

pkg/extension/host.go

@@ -0,0 +1,34 @@
+package extension
+
+import (
+	"github.com/inbucket/inbucket/pkg/extension/event"
+)
+
+// Host defines extension points for Inbucket.
+type Host struct {
+	Events *Events
+}
+
+// Events defines all the event types supported by the extension host.
+//
+// Before-events provide an opportunity for extensions to alter how Inbucket responds to that type
+// of event.  These events are processed synchronously; expensive operations will reduce the
+// perceived performance of Inbucket.  The first listener in the list to respond with a non-nil
+// value will determine the response, and the remaining listeners will not be called.
+//
+// After-events allow extensions to take an action after an event has completed.  These events are
+// processed asynchronously with respect to the rest of Inbuckets operation.  However, an event
+// listener will not be called until the one before it complets.
+type Events struct {
+	AfterMessageDeleted AsyncEventBroker[event.MessageMetadata]
+	AfterMessageStored  AsyncEventBroker[event.MessageMetadata]
+	BeforeMailAccepted  EventBroker[event.AddressParts, bool]
+}
+
+// Void indicates the event emitter will ignore any value returned by listeners.
+type Void struct{}
+
+// NewHost creates a new extension host.
+func NewHost() *Host {
+	return &Host{Events: &Events{}}
+}

pkg/extension/luahost/bind_address.go

@@ -0,0 +1,92 @@
+package luahost
+
+import (
+	"net/mail"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+const mailAddressName = "address"
+
+func registerMailAddressType(ls *lua.LState) {
+	mt := ls.NewTypeMetatable(mailAddressName)
+	ls.SetGlobal(mailAddressName, mt)
+
+	// Static attributes.
+	ls.SetField(mt, "new", ls.NewFunction(newMailAddress))
+
+	// Methods.
+	ls.SetField(mt, "__index", ls.NewFunction(mailAddressIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(mailAddressNewIndex))
+}
+
+func newMailAddress(ls *lua.LState) int {
+	val := &mail.Address{
+		Name:    ls.CheckString(1),
+		Address: ls.CheckString(2),
+	}
+	ud := wrapMailAddress(ls, val)
+	ls.Push(ud)
+
+	return 1
+}
+
+func wrapMailAddress(ls *lua.LState, val *mail.Address) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(mailAddressName))
+
+	return ud
+}
+
+func unwrapMailAddress(ud *lua.LUserData) (*mail.Address, bool) {
+	val, ok := ud.Value.(*mail.Address)
+	return val, ok
+}
+
+func checkMailAddress(ls *lua.LState, pos int) *mail.Address {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*mail.Address); ok {
+		return val
+	}
+	ls.ArgError(1, mailAddressName+" expected")
+	return nil
+}
+
+// Gets a field value from MailAddress user object.  This emulates a Lua table,
+// allowing `msg.subject` instead of a Lua object syntax of `msg:subject()`.
+func mailAddressIndex(ls *lua.LState) int {
+	a := checkMailAddress(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "name":
+		ls.Push(lua.LString(a.Name))
+	case "address":
+		ls.Push(lua.LString(a.Address))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// Sets a field value on MailAddress user object.  This emulates a Lua table,
+// allowing `msg.subject = x` instead of a Lua object syntax of `msg:subject(x)`.
+func mailAddressNewIndex(ls *lua.LState) int {
+	a := checkMailAddress(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "name":
+		a.Name = ls.CheckString(3)
+	case "address":
+		a.Address = ls.CheckString(3)
+	default:
+		ls.RaiseError("invalid index %q", index)
+	}
+
+	return 0
+}

pkg/extension/luahost/bind_address_test.go

@@ -0,0 +1,54 @@
+package luahost
+
+import (
+	"net/mail"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+)
+
+func TestMailAddressGetters(t *testing.T) {
+	want := &mail.Address{
+		Name:    "Roberto I",
+		Address: "ri@example.com",
+	}
+	script := `
+		assert(addr, "addr should not be nil")
+
+		want = "Roberto I"
+		got = addr.name
+		assert(got == want, string.format("got name %q, want %q", got, want))
+
+		want = "ri@example.com"
+		got = addr.address
+		assert(got == want, string.format("got address %q, want %q", got, want))
+	`
+
+	ls := lua.NewState()
+	registerMailAddressType(ls)
+	ls.SetGlobal("addr", wrapMailAddress(ls, want))
+	require.NoError(t, ls.DoString(script))
+}
+
+func TestMailAddressSetters(t *testing.T) {
+	want := &mail.Address{
+		Name:    "Roberto I",
+		Address: "ri@example.com",
+	}
+	script := `
+		assert(addr, "addr should not be nil")
+
+		addr.name = "Roberto I"
+		addr.address = "ri@example.com"
+	`
+
+	got := &mail.Address{}
+	ls := lua.NewState()
+	registerMailAddressType(ls)
+	ls.SetGlobal("addr", wrapMailAddress(ls, got))
+	require.NoError(t, ls.DoString(script))
+
+	assert.Equal(t, want, got)
+}

pkg/extension/luahost/bind_inbucket.go

@@ -0,0 +1,218 @@
+package luahost
+
+import (
+	"errors"
+	"fmt"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+const (
+	inbucketName       = "inbucket"
+	inbucketBeforeName = "inbucket_before"
+	inbucketAfterName  = "inbucket_after"
+)
+
+// Inbucket is the primary Lua interface data structure.
+type Inbucket struct {
+	After  InbucketAfterFuncs
+	Before InbucketBeforeFuncs
+}
+
+// InbucketAfterFuncs holds references to Lua extension functions to be called async
+// after Inbucket handles an event.
+type InbucketAfterFuncs struct {
+	MessageDeleted *lua.LFunction
+	MessageStored  *lua.LFunction
+}
+
+// InbucketBeforeFuncs holds references to Lua extension functions to be called
+// before Inbucket handles an event.
+type InbucketBeforeFuncs struct {
+	MailAccepted *lua.LFunction
+}
+
+func registerInbucketTypes(ls *lua.LState) {
+	// inbucket type.
+	mt := ls.NewTypeMetatable(inbucketName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketIndex))
+
+	// inbucket global var.
+	ud := wrapInbucket(ls, &Inbucket{})
+	ls.SetGlobal(inbucketName, ud)
+
+	// inbucket.after type.
+	mt = ls.NewTypeMetatable(inbucketAfterName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketAfterIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(inbucketAfterNewIndex))
+
+	// inbucket.before type.
+	mt = ls.NewTypeMetatable(inbucketBeforeName)
+	ls.SetField(mt, "__index", ls.NewFunction(inbucketBeforeIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(inbucketBeforeNewIndex))
+}
+
+func wrapInbucket(ls *lua.LState, val *Inbucket) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketName))
+
+	return ud
+}
+
+func wrapInbucketAfter(ls *lua.LState, val *InbucketAfterFuncs) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketAfterName))
+
+	return ud
+}
+
+func wrapInbucketBefore(ls *lua.LState, val *InbucketBeforeFuncs) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(inbucketBeforeName))
+
+	return ud
+}
+
+func getInbucket(ls *lua.LState) (*Inbucket, error) {
+	lv := ls.GetGlobal(inbucketName)
+	if lv == nil {
+		return nil, errors.New("inbucket object was nil")
+	}
+
+	ud, ok := lv.(*lua.LUserData)
+	if !ok {
+		return nil, fmt.Errorf("inbucket object was type %s instead of UserData", lv.Type())
+	}
+
+	val, ok := ud.Value.(*Inbucket)
+	if !ok {
+		return nil, fmt.Errorf("inbucket object (%v) could not be cast", ud.Value)
+	}
+
+	return val, nil
+}
+
+func checkInbucket(ls *lua.LState, pos int) *Inbucket {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*Inbucket); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketName+" expected")
+	return nil
+}
+
+func checkInbucketAfter(ls *lua.LState, pos int) *InbucketAfterFuncs {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*InbucketAfterFuncs); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketAfterName+" expected")
+	return nil
+}
+
+func checkInbucketBefore(ls *lua.LState, pos int) *InbucketBeforeFuncs {
+	ud := ls.CheckUserData(pos)
+	if val, ok := ud.Value.(*InbucketBeforeFuncs); ok {
+		return val
+	}
+	ls.ArgError(1, inbucketBeforeName+" expected")
+	return nil
+}
+
+// inbucket getter.
+func inbucketIndex(ls *lua.LState) int {
+	ib := checkInbucket(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "after":
+		ls.Push(wrapInbucketAfter(ls, &ib.After))
+	case "before":
+		ls.Push(wrapInbucketBefore(ls, &ib.Before))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.after getter.
+func inbucketAfterIndex(ls *lua.LState) int {
+	after := checkInbucketAfter(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "message_deleted":
+		ls.Push(funcOrNil(after.MessageDeleted))
+	case "message_stored":
+		ls.Push(funcOrNil(after.MessageStored))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.after setter.
+func inbucketAfterNewIndex(ls *lua.LState) int {
+	m := checkInbucketAfter(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "message_deleted":
+		m.MessageDeleted = ls.CheckFunction(3)
+	case "message_stored":
+		m.MessageStored = ls.CheckFunction(3)
+	default:
+		ls.RaiseError("invalid inbucket.after index %q", index)
+	}
+
+	return 0
+}
+
+// inbucket.before getter.
+func inbucketBeforeIndex(ls *lua.LState) int {
+	before := checkInbucketBefore(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "mail_accepted":
+		ls.Push(funcOrNil(before.MailAccepted))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// inbucket.before setter.
+func inbucketBeforeNewIndex(ls *lua.LState) int {
+	m := checkInbucketBefore(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "mail_accepted":
+		m.MailAccepted = ls.CheckFunction(3)
+	default:
+		ls.RaiseError("invalid inbucket.before index %q", index)
+	}
+
+	return 0
+}
+
+func funcOrNil(f *lua.LFunction) lua.LValue {
+	if f == nil {
+		return lua.LNil
+	}
+
+	return f
+}

pkg/extension/luahost/bind_inbucket_test.go

@@ -0,0 +1,102 @@
+package luahost
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+)
+
+func TestInbucketAfterFuncs(t *testing.T) {
+	// This Script registers each function and calls it.  No effort is made to use the arguments
+	// that Inbucket expects, this is only to validate the inbucket.after data structure getters
+	// and setters.
+	script := `
+		assert(inbucket, "inbucket should not be nil")
+		assert(inbucket.after, "inbucket.after should not be nil")
+
+		local fns = { "message_deleted", "message_stored" }
+
+		-- Verify functions start off nil.
+		for i, name in ipairs(fns) do
+			assert(inbucket.after[name] == nil, "after." .. name .. " should be nil")
+		end
+
+		-- Test function to track func calls made, ensures no crossed wires.
+		local calls = {}
+		function makeTestFunc(create_name)
+			return function(call_name)
+				calls[create_name] = call_name
+			end
+		end
+
+		-- Set after functions, verify not nil, and call them.
+		for i, name in ipairs(fns) do
+			inbucket.after[name] = makeTestFunc(name)
+			assert(inbucket.after[name], "after." .. name .. " should not be nil")
+		end
+
+		-- Call each function.  Separate loop to verify final state in 'calls'.
+		for i, name in ipairs(fns) do
+			inbucket.after[name](name)
+		end
+
+		-- Verify functions were called.
+		for i, name in ipairs(fns) do
+			assert(calls[name], "after." .. name .. " should have been called")
+			assert(calls[name] == name,
+				string.format("after.%s was called with incorrect argument %s", name, calls[name]))
+		end
+	`
+
+	ls := lua.NewState()
+	registerInbucketTypes(ls)
+	require.NoError(t, ls.DoString(script))
+}
+
+func TestInbucketBeforeFuncs(t *testing.T) {
+	// This Script registers each function and calls it.  No effort is made to use the arguments
+	// that Inbucket expects, this is only to validate the inbucket.before data structure getters
+	// and setters.
+	script := `
+		assert(inbucket, "inbucket should not be nil")
+		assert(inbucket.before, "inbucket.before should not be nil")
+
+		local fns = { "mail_accepted" }
+
+		-- Verify functions start off nil.
+		for i, name in ipairs(fns) do
+			assert(inbucket.before[name] == nil, "before." .. name .. " should be nil")
+		end
+
+		-- Test function to track func calls made, ensures no crossed wires.
+		local calls = {}
+		function makeTestFunc(create_name)
+			return function(call_name)
+				calls[create_name] = call_name
+			end
+		end
+
+		-- Set before functions, verify not nil, and call them.
+		for i, name in ipairs(fns) do
+			inbucket.before[name] = makeTestFunc(name)
+			assert(inbucket.before[name], "before." .. name .. " should not be nil")
+		end
+
+		-- Call each function.  Separate loop to verify final state in 'calls'.
+		for i, name in ipairs(fns) do
+			inbucket.before[name](name)
+		end
+
+		-- Verify functions were called.
+		for i, name in ipairs(fns) do
+			assert(calls[name], "before." .. name .. " should have been called")
+			assert(calls[name] == name,
+				string.format("before.%s was called with incorrect argument %s", name, calls[name]))
+		end
+	`
+
+	ls := lua.NewState()
+	registerInbucketTypes(ls)
+	require.NoError(t, ls.DoString(script))
+}

pkg/extension/luahost/bind_message.go

@@ -0,0 +1,119 @@
+package luahost
+
+import (
+	"net/mail"
+	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	lua "github.com/yuin/gopher-lua"
+)
+
+const messageMetadataName = "message_metadata"
+
+func registerMessageMetadataType(ls *lua.LState) {
+	mt := ls.NewTypeMetatable(messageMetadataName)
+	ls.SetGlobal(messageMetadataName, mt)
+
+	// Static attributes.
+	ls.SetField(mt, "new", ls.NewFunction(newMessageMetadata))
+
+	// Methods.
+	ls.SetField(mt, "__index", ls.NewFunction(messageMetadataIndex))
+	ls.SetField(mt, "__newindex", ls.NewFunction(messageMetadataNewIndex))
+}
+
+func newMessageMetadata(ls *lua.LState) int {
+	val := &event.MessageMetadata{}
+	ud := wrapMessageMetadata(ls, val)
+	ls.Push(ud)
+
+	return 1
+}
+
+func wrapMessageMetadata(ls *lua.LState, val *event.MessageMetadata) *lua.LUserData {
+	ud := ls.NewUserData()
+	ud.Value = val
+	ls.SetMetatable(ud, ls.GetTypeMetatable(messageMetadataName))
+
+	return ud
+}
+
+func checkMessageMetadata(ls *lua.LState, pos int) *event.MessageMetadata {
+	ud := ls.CheckUserData(pos)
+	if v, ok := ud.Value.(*event.MessageMetadata); ok {
+		return v
+	}
+	ls.ArgError(1, messageMetadataName+" expected")
+	return nil
+}
+
+// Gets a field value from MessageMetadata user object.  This emulates a Lua table,
+// allowing `msg.subject` instead of a Lua object syntax of `msg:subject()`.
+func messageMetadataIndex(ls *lua.LState) int {
+	m := checkMessageMetadata(ls, 1)
+	field := ls.CheckString(2)
+
+	// Push the requested field's value onto the stack.
+	switch field {
+	case "mailbox":
+		ls.Push(lua.LString(m.Mailbox))
+	case "id":
+		ls.Push(lua.LString(m.ID))
+	case "from":
+		ls.Push(wrapMailAddress(ls, m.From))
+	case "to":
+		lt := &lua.LTable{}
+		for _, v := range m.To {
+			lt.Append(wrapMailAddress(ls, v))
+		}
+		ls.Push(lt)
+	case "date":
+		ls.Push(lua.LNumber(m.Date.Unix()))
+	case "subject":
+		ls.Push(lua.LString(m.Subject))
+	case "size":
+		ls.Push(lua.LNumber(m.Size))
+	default:
+		// Unknown field.
+		ls.Push(lua.LNil)
+	}
+
+	return 1
+}
+
+// Sets a field value on MessageMetadata user object.  This emulates a Lua table,
+// allowing `msg.subject = x` instead of a Lua object syntax of `msg:subject(x)`.
+func messageMetadataNewIndex(ls *lua.LState) int {
+	m := checkMessageMetadata(ls, 1)
+	index := ls.CheckString(2)
+
+	switch index {
+	case "mailbox":
+		m.Mailbox = ls.CheckString(3)
+	case "id":
+		m.ID = ls.CheckString(3)
+	case "from":
+		m.From = checkMailAddress(ls, 3)
+	case "to":
+		lt := ls.CheckTable(3)
+		to := make([]*mail.Address, 0, 16)
+		lt.ForEach(func(k, lv lua.LValue) {
+			if ud, ok := lv.(*lua.LUserData); ok {
+				if entry, ok := unwrapMailAddress(ud); ok {
+					to = append(to, entry)
+				}
+			}
+		})
+		m.To = to
+	case "date":
+		m.Date = time.Unix(ls.CheckInt64(3), 0)
+	case "subject":
+		m.Subject = ls.CheckString(3)
+	case "size":
+		m.Size = ls.CheckInt64(3)
+	default:
+		ls.RaiseError("invalid index %q", index)
+	}
+
+	return 0
+}

pkg/extension/luahost/bind_message_test.go

@@ -0,0 +1,91 @@
+package luahost
+
+import (
+	"net/mail"
+	"testing"
+	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+)
+
+func TestMessageMetadataGetters(t *testing.T) {
+	want := &event.MessageMetadata{
+		Mailbox: "mb1",
+		ID:      "id1",
+		From:    &mail.Address{Name: "name1", Address: "addr1"},
+		To:      []*mail.Address{{Name: "name2", Address: "addr2"}},
+		Date:    time.Date(2001, time.February, 3, 4, 5, 6, 0, time.UTC),
+		Subject: "subj1",
+		Size:    42,
+	}
+	script := `
+		assert(msg, "msg should not be nil")
+
+		function assert_eq(got, want)
+			assert(got == want, string.format("got name %q, wanted %q", got, want))
+		end
+
+		assert_eq(msg.mailbox, "mb1")
+		assert_eq(msg.id, "id1")
+		assert_eq(msg.subject, "subj1")
+		assert_eq(msg.size, 42)
+
+		assert_eq(msg.from.name, "name1")
+		assert_eq(msg.from.address, "addr1")
+
+		assert_eq(table.getn(msg.to), 1)
+		assert_eq(msg.to[1].name, "name2")
+		assert_eq(msg.to[1].address, "addr2")
+
+		assert_eq(msg.date, 981173106)
+	`
+
+	ls := lua.NewState()
+	registerMessageMetadataType(ls)
+	registerMailAddressType(ls)
+	ls.SetGlobal("msg", wrapMessageMetadata(ls, want))
+	require.NoError(t, ls.DoString(script))
+}
+
+func TestMessageMetadataSetters(t *testing.T) {
+	want := &event.MessageMetadata{
+		Mailbox: "mb1",
+		ID:      "id1",
+		From:    &mail.Address{Name: "name1", Address: "addr1"},
+		To:      []*mail.Address{{Name: "name2", Address: "addr2"}},
+		Date:    time.Date(2001, time.February, 3, 4, 5, 6, 0, time.UTC),
+		Subject: "subj1",
+		Size:    42,
+	}
+	script := `
+		assert(msg, "msg should not be nil")
+
+		msg.mailbox = "mb1"
+		msg.id = "id1"
+		msg.subject = "subj1"
+		msg.size = 42
+
+		msg.from = address.new("name1", "addr1")
+		msg.to = { address.new("name2", "addr2") }
+
+		msg.date = 981173106
+	`
+
+	got := &event.MessageMetadata{}
+	ls := lua.NewState()
+	registerMessageMetadataType(ls)
+	registerMailAddressType(ls)
+	ls.SetGlobal("msg", wrapMessageMetadata(ls, got))
+	require.NoError(t, ls.DoString(script))
+
+	// Timezones will cause a naive comparison to fail.
+	assert.Equal(t, want.Date.Unix(), got.Date.Unix())
+	now := time.Now()
+	want.Date = now
+	got.Date = now
+
+	assert.Equal(t, want, got)
+}

pkg/extension/luahost/bind_policy.go

@@ -0,0 +1,17 @@
+package luahost
+
+import (
+	lua "github.com/yuin/gopher-lua"
+)
+
+const policyName = "policy"
+
+func registerPolicyType(ls *lua.LState) {
+	mt := ls.NewTypeMetatable(policyName)
+	ls.SetGlobal(policyName, mt)
+
+	// Static attributes.
+	ls.SetField(mt, "allow", lua.LTrue)
+	ls.SetField(mt, "deny", lua.LFalse)
+	ls.SetField(mt, "defer", lua.LNil)
+}

pkg/extension/luahost/lua.go

@@ -0,0 +1,195 @@
+package luahost
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+	lua "github.com/yuin/gopher-lua"
+	"github.com/yuin/gopher-lua/parse"
+)
+
+// Host of Lua extensions.
+type Host struct {
+	extHost    *extension.Host
+	pool       *statePool
+	logContext zerolog.Context
+}
+
+// New constructs a new Lua Host, pre-compiling the source.
+func New(conf config.Lua, extHost *extension.Host) (*Host, error) {
+	scriptPath := conf.Path
+	if scriptPath == "" {
+		return nil, nil
+	}
+
+	logContext := log.With().Str("module", "lua")
+	logger := logContext.Str("phase", "startup").Str("path", scriptPath).Logger()
+
+	// Pre-load, parse, and compile script.
+	if fi, err := os.Stat(scriptPath); err != nil {
+		logger.Info().Msg("Script file not found")
+		return nil, nil
+	} else if fi.IsDir() {
+		return nil, fmt.Errorf("Lua script %v is a directory", scriptPath)
+	}
+
+	logger.Info().Msg("Loading script")
+	file, err := os.Open(scriptPath)
+	defer file.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewFromReader(extHost, bufio.NewReader(file), scriptPath)
+}
+
+// NewFromReader constructs a new Lua Host, loading Lua source from the provided reader.
+// The provided path is used in logging and error messages.
+func NewFromReader(extHost *extension.Host, r io.Reader, path string) (*Host, error) {
+	logContext := log.With().Str("module", "lua")
+	logger := logContext.Str("phase", "startup").Str("path", path).Logger()
+
+	// Pre-parse, and compile script.
+	chunk, err := parse.Parse(r, path)
+	if err != nil {
+		return nil, err
+	}
+	proto, err := lua.Compile(chunk, path)
+	if err != nil {
+		return nil, err
+	}
+
+	// Build the pool and confirm LState is retrievable.
+	pool := newStatePool(proto)
+	h := &Host{extHost: extHost, pool: pool, logContext: logContext}
+	if ls, err := pool.getState(); err == nil {
+		h.wireFunctions(logger, ls)
+
+		// State creation works, put it back.
+		pool.putState(ls)
+	} else {
+		return nil, err
+	}
+
+	return h, nil
+}
+
+// CreateChannel creates a channel and places it into the named global variable
+// in newly created LStates.
+func (h *Host) CreateChannel(name string) chan lua.LValue {
+	return h.pool.createChannel(name)
+}
+
+// Detects global lua event listener functions and wires them up.
+func (h *Host) wireFunctions(logger zerolog.Logger, ls *lua.LState) {
+	ib, err := getInbucket(ls)
+	if err != nil {
+		logger.Fatal().Err(err).Msg("Failed to get inbucket global")
+	}
+
+	events := h.extHost.Events
+	const listenerName string = "lua"
+
+	if ib.After.MessageDeleted != nil {
+		events.AfterMessageDeleted.AddListener(listenerName, h.handleAfterMessageDeleted)
+	}
+	if ib.After.MessageStored != nil {
+		events.AfterMessageStored.AddListener(listenerName, h.handleAfterMessageStored)
+	}
+	if ib.Before.MailAccepted != nil {
+		events.BeforeMailAccepted.AddListener(listenerName, h.handleBeforeMailAccepted)
+	}
+}
+
+func (h *Host) handleAfterMessageDeleted(msg event.MessageMetadata) {
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_deleted")
+	if !ok {
+		return
+	}
+	defer h.pool.putState(ls)
+
+	// Call lua function.
+	logger.Debug().Msgf("Calling Lua function with %+v", msg)
+	if err := ls.CallByParam(
+		lua.P{Fn: ib.After.MessageDeleted, NRet: 0, Protect: true},
+		wrapMessageMetadata(ls, &msg),
+	); err != nil {
+		logger.Error().Err(err).Msg("Failed to call Lua function")
+	}
+}
+
+func (h *Host) handleAfterMessageStored(msg event.MessageMetadata) {
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_stored")
+	if !ok {
+		return
+	}
+	defer h.pool.putState(ls)
+
+	// Call lua function.
+	logger.Debug().Msgf("Calling Lua function with %+v", msg)
+	if err := ls.CallByParam(
+		lua.P{Fn: ib.After.MessageStored, NRet: 0, Protect: true},
+		wrapMessageMetadata(ls, &msg),
+	); err != nil {
+		logger.Error().Err(err).Msg("Failed to call Lua function")
+	}
+}
+
+func (h *Host) handleBeforeMailAccepted(addr event.AddressParts) *bool {
+	logger, ls, ib, ok := h.prepareInbucketFuncCall("after.message_stored")
+	if !ok {
+		return nil
+	}
+	defer h.pool.putState(ls)
+
+	logger.Debug().Msgf("Calling Lua function with %+v", addr)
+	if err := ls.CallByParam(
+		lua.P{Fn: ib.Before.MailAccepted, NRet: 1, Protect: true},
+		lua.LString(addr.Local),
+		lua.LString(addr.Domain),
+	); err != nil {
+		logger.Error().Err(err).Msg("Failed to call Lua function")
+		return nil
+	}
+
+	lval := ls.Get(1)
+	ls.Pop(1)
+	logger.Debug().Msgf("Lua function returned %q (%v)", lval, lval.Type().String())
+
+	if lval.Type() == lua.LTNil {
+		return nil
+	}
+
+	result := true
+	if lua.LVIsFalse(lval) {
+		result = false
+	}
+
+	return &result
+}
+
+// Common preparation for calling Lua functions.
+func (h *Host) prepareInbucketFuncCall(funcName string) (logger zerolog.Logger, ls *lua.LState, ib *Inbucket, ok bool) {
+	logger = h.logContext.Str("event", funcName).Logger()
+
+	ls, err := h.pool.getState()
+	if err != nil {
+		logger.Error().Err(err).Msg("Failed to get Lua state instance from pool")
+		return logger, nil, nil, false
+	}
+
+	ib, err = getInbucket(ls)
+	if err != nil {
+		logger.Error().Err(err).Msg("Failed to obtain Lua inbucket object")
+		return logger, nil, nil, false
+	}
+
+	return logger, ls, ib, true
+}

pkg/extension/luahost/lua_test.go

@@ -0,0 +1,166 @@
+package luahost_test
+
+import (
+	"net/mail"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/inbucket/inbucket/pkg/extension/luahost"
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+)
+
+// LuaInit holds useful test globals.
+const LuaInit = `
+	async = false
+	test_ok = true
+
+	-- Sends marks tests failed instead of erroring when enabled.
+	function assert_async(value, message)
+		if not value then
+			if async then
+				print(message)
+				test_ok = false
+			else
+				error(message)
+			end
+		end
+	end
+
+	-- Tests plain values and list-style tables.
+	function assert_eq(got, want)
+		if type(got) == "table" and type(want) == "table" then
+			assert_async(#got == #want, string.format("got %d elements, wanted %d", #got, #want))
+
+			for i, gotv in ipairs(got) do
+				local wantv = want[i]
+				assert_eq(gotv, wantv, "got[%d] = %q, wanted %q", gotv, wantv)
+			end
+
+			return
+		end
+
+		assert_async(got == want, string.format("got %q, wanted %q", got, want))
+	end
+
+	function assert_contains(got, want)
+		assert_async(string.find(got, want),
+			string.format("got %q, wanted it to contain %q", got, want))
+	end
+`
+
+func TestEmptyScript(t *testing.T) {
+	script := ""
+	extHost := extension.NewHost()
+
+	_, err := luahost.NewFromReader(extHost, strings.NewReader(script), "test.lua")
+	require.NoError(t, err)
+}
+
+func TestAfterMessageDeleted(t *testing.T) {
+	// Register lua event listener, setup notify channel.
+	script := `
+		async = true
+
+		function inbucket.after.message_deleted(msg)
+			-- Full message bindings tested elsewhere.
+			assert_eq(msg.mailbox, "mb1")
+			assert_eq(msg.id, "id1")
+			notify:send(test_ok)
+		end
+	`
+	extHost := extension.NewHost()
+	luaHost, err := luahost.NewFromReader(extHost, strings.NewReader(LuaInit+script), "test.lua")
+	require.NoError(t, err)
+	notify := luaHost.CreateChannel("notify")
+
+	// Send event, check channel response is true.
+	msg := &event.MessageMetadata{
+		Mailbox: "mb1",
+		ID:      "id1",
+		From:    &mail.Address{Name: "name1", Address: "addr1"},
+		To:      []*mail.Address{{Name: "name2", Address: "addr2"}},
+		Date:    time.Date(2001, time.February, 3, 4, 5, 6, 0, time.UTC),
+		Subject: "subj1",
+		Size:    42,
+	}
+	extHost.Events.AfterMessageDeleted.Emit(msg)
+	assertNotified(t, notify)
+}
+
+func TestAfterMessageStored(t *testing.T) {
+	// Register lua event listener, setup notify channel.
+	script := `
+		async = true
+
+		function inbucket.after.message_stored(msg)
+			-- Full message bindings tested elsewhere.
+			assert_eq(msg.mailbox, "mb1")
+			assert_eq(msg.id, "id1")
+			notify:send(test_ok)
+		end
+	`
+	extHost := extension.NewHost()
+	luaHost, err := luahost.NewFromReader(extHost, strings.NewReader(LuaInit+script), "test.lua")
+	require.NoError(t, err)
+	notify := luaHost.CreateChannel("notify")
+
+	// Send event, check channel response is true.
+	msg := &event.MessageMetadata{
+		Mailbox: "mb1",
+		ID:      "id1",
+		From:    &mail.Address{Name: "name1", Address: "addr1"},
+		To:      []*mail.Address{{Name: "name2", Address: "addr2"}},
+		Date:    time.Date(2001, time.February, 3, 4, 5, 6, 0, time.UTC),
+		Subject: "subj1",
+		Size:    42,
+	}
+	extHost.Events.AfterMessageStored.Emit(msg)
+	assertNotified(t, notify)
+}
+
+func TestBeforeMailAccepted(t *testing.T) {
+	// Register lua event listener.
+	script := `
+		function inbucket.before.mail_accepted(localpart, domain)
+			return localpart == "from" and domain == "test"
+		end
+	`
+	extHost := extension.NewHost()
+	_, err := luahost.NewFromReader(extHost, strings.NewReader(script), "test.lua")
+	require.NoError(t, err)
+
+	// Send event to be accepted.
+	addr := &event.AddressParts{Local: "from", Domain: "test"}
+	got := extHost.Events.BeforeMailAccepted.Emit(addr)
+	want := true
+	require.NotNil(t, got)
+	if *got != want {
+		t.Errorf("Got %v, wanted %v for addr %v", *got, want, addr)
+	}
+
+	// Send event to be denied.
+	addr = &event.AddressParts{Local: "reject", Domain: "me"}
+	got = extHost.Events.BeforeMailAccepted.Emit(addr)
+	want = false
+	require.NotNil(t, got)
+	if *got != want {
+		t.Errorf("Got %v, wanted %v for addr %v", *got, want, addr)
+	}
+}
+
+func assertNotified(t *testing.T, notify chan lua.LValue) {
+	t.Helper()
+	select {
+	case reslv := <-notify:
+		// Lua function received event.
+		if lua.LVIsFalse(reslv) {
+			t.Error("Lua responsed with false, wanted true")
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("Lua did not respond to event within timeout")
+	}
+}

pkg/extension/luahost/pool.go

@@ -0,0 +1,104 @@
+package luahost
+
+import (
+	"net/http"
+	"sync"
+
+	"github.com/cjoudrey/gluahttp"
+	"github.com/inbucket/gopher-json"
+	lua "github.com/yuin/gopher-lua"
+)
+
+type statePool struct {
+	sync.Mutex
+	funcProto *lua.FunctionProto         // Compiled lua.
+	states    []*lua.LState              // Pool of available LStates.
+	channels  map[string]chan lua.LValue // Global interop channels.
+}
+
+func newStatePool(funcProto *lua.FunctionProto) *statePool {
+	return &statePool{
+		funcProto: funcProto,
+		channels:  make(map[string]chan lua.LValue),
+	}
+}
+
+// newState creates a new LState and configures it. Lock must be held.
+func (lp *statePool) newState() (*lua.LState, error) {
+	ls := lua.NewState()
+
+	// Load supplemental native modules.
+	ls.PreloadModule("http", gluahttp.NewHttpModule(&http.Client{}).Loader)
+	ls.PreloadModule("json", json.Loader)
+
+	// Setup channels.
+	for name, ch := range lp.channels {
+		ls.SetGlobal(name, lua.LChannel(ch))
+	}
+
+	// Register custom types.
+	registerInbucketTypes(ls)
+	registerMessageMetadataType(ls)
+	registerMailAddressType(ls)
+	registerPolicyType(ls)
+
+	// Run compiled script.
+	ls.Push(ls.NewFunctionFromProto(lp.funcProto))
+	if err := ls.PCall(0, lua.MultRet, nil); err != nil {
+		return nil, err
+	}
+
+	return ls, nil
+}
+
+// getState returns a free LState, or creates a new one.
+func (lp *statePool) getState() (*lua.LState, error) {
+	lp.Lock()
+	defer lp.Unlock()
+
+	ln := len(lp.states)
+	if ln == 0 {
+		return lp.newState()
+	}
+
+	state := lp.states[ln-1]
+	lp.states = lp.states[0 : ln-1]
+
+	return state, nil
+}
+
+// putState returns the LState to the pool.
+func (lp *statePool) putState(state *lua.LState) {
+	if state.IsClosed() {
+		return
+	}
+
+	// Clear stack.
+	state.Pop(state.GetTop())
+
+	lp.Lock()
+	defer lp.Unlock()
+
+	lp.states = append(lp.states, state)
+}
+
+// createChannel creates a new channel, which will become a global variable in
+// newly created LStates.  We also destroy any pooled states.
+//
+// Warning: There may still be checked out LStates that will not have the value
+// set, which could be put back into the pool.
+func (lp *statePool) createChannel(name string) chan lua.LValue {
+	lp.Lock()
+	defer lp.Unlock()
+
+	ch := make(chan lua.LValue, 10)
+	lp.channels[name] = ch
+
+	// Flush state pool.
+	for _, s := range lp.states {
+		s.Close()
+	}
+	lp.states = lp.states[:0]
+
+	return ch
+}

pkg/extension/luahost/pool_test.go

@@ -0,0 +1,101 @@
+package luahost
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+	"github.com/yuin/gopher-lua/parse"
+)
+
+func makeEmptyPool() *statePool {
+	source := strings.NewReader("-- Empty source")
+
+	chunk, err := parse.Parse(source, "from string")
+	if err != nil {
+		panic(err)
+	}
+
+	proto, err := lua.Compile(chunk, "from string")
+	if err != nil {
+		panic(err)
+	}
+
+	return newStatePool(proto)
+}
+
+func TestPoolGetsDistinct(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	b, err := pool.getState()
+	require.NoError(t, err)
+
+	if a == b {
+		t.Error("Got pool a == b, expected distinct pools")
+	}
+}
+
+func TestPoolGrowsWithPuts(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	b, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	pool.putState(a)
+	pool.putState(b)
+
+	want := 2
+	if got := len(pool.states); got != want {
+		t.Errorf("len pool.states got %v, want %v", got, want)
+	}
+}
+
+// Closed LStates should not be added to the pool.
+func TestPoolPutDiscardsClosed(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	a.Close()
+	pool.putState(a)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to remain empty")
+}
+
+func TestPoolPutClearsStack(t *testing.T) {
+	pool := makeEmptyPool()
+
+	ls, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	// Setup stack.
+	ls.Push(lua.LNumber(4))
+	ls.Push(lua.LString("bacon"))
+	require.Equal(t, 2, ls.GetTop(), "Want stack to have two items")
+
+	// Return and verify stack cleared.
+	pool.putState(ls)
+	assert.Equal(t, 1, len(pool.states), "Wanted pool to have one item")
+	require.Equal(t, 0, ls.GetTop(), "Want stack to be empty")
+}
+
+func TestPoolSetsChannels(t *testing.T) {
+	pool := makeEmptyPool()
+	pool.createChannel("test_chan")
+
+	s, err := pool.getState()
+	require.NoError(t, err)
+
+	got := s.GetGlobal("test_chan")
+	assert.Equal(t, lua.LTChannel, got.Type(),
+		"Got global type %v, wanted LTChannel", got.Type().String())
+}

pkg/message/manager.go

@@ -7,10 +7,10 @@ import (
 	"strings"
 	"time"
 
-	"github.com/inbucket/inbucket/pkg/msghub"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/policy"
 	"github.com/inbucket/inbucket/pkg/storage"
-	"github.com/inbucket/inbucket/pkg/stringutil"
 	"github.com/jhillyerd/enmime"
 	"github.com/rs/zerolog/log"
 )
@@ -24,7 +24,7 @@ type Manager interface {
 		prefix string,
 		content []byte,
 	) (id string, err error)
-	GetMetadata(mailbox string) ([]*Metadata, error)
+	GetMetadata(mailbox string) ([]*event.MessageMetadata, error)
 	GetMessage(mailbox, id string) (*Message, error)
 	MarkSeen(mailbox, id string) error
 	PurgeMessages(mailbox string) error
@@ -37,7 +37,7 @@ type Manager interface {
 type StoreManager struct {
 	AddrPolicy *policy.Addressing
 	Store      storage.Store
-	Hub        *msghub.Hub
+	ExtHost    *extension.Host
 }
 
 // Deliver submits a new message to the store.
@@ -65,9 +65,10 @@ func (s *StoreManager) Deliver(
 			toaddr[i] = &torecip.Address
 		}
 	}
+
 	log.Debug().Str("module", "message").Str("mailbox", to.Mailbox).Msg("Delivering message")
 	delivery := &Delivery{
-		Meta: Metadata{
+		Meta: event.MessageMetadata{
 			Mailbox: to.Mailbox,
 			From:    fromaddr[0],
 			To:      toaddr,
@@ -80,31 +81,24 @@ func (s *StoreManager) Deliver(
 	if err != nil {
 		return "", err
 	}
-	if s.Hub != nil {
+
-		// Broadcast message information.
+	// Emit message stored event.
-		broadcast := msghub.Message{
+	event := delivery.Meta
-			Mailbox: to.Mailbox,
+	event.ID = id
-			ID:      id,
+	s.ExtHost.Events.AfterMessageStored.Emit(&event)
-			From:    stringutil.StringAddress(delivery.From()),
+
-			To:      stringutil.StringAddressList(delivery.To()),
-			Subject: delivery.Subject(),
-			Date:    delivery.Date(),
-			Size:    delivery.Size(),
-		}
-		s.Hub.Dispatch(broadcast)
-	}
 	return id, nil
 }
 
 // GetMetadata returns a slice of metadata for the specified mailbox.
-func (s *StoreManager) GetMetadata(mailbox string) ([]*Metadata, error) {
+func (s *StoreManager) GetMetadata(mailbox string) ([]*event.MessageMetadata, error) {
 	messages, err := s.Store.GetMessages(mailbox)
 	if err != nil {
 		return nil, err
 	}
-	metas := make([]*Metadata, len(messages))
+	metas := make([]*event.MessageMetadata, len(messages))
 	for i, sm := range messages {
-		metas[i] = makeMetadata(sm)
+		metas[i] = MakeMetadata(sm)
 	}
 	return metas, nil
 }
@@ -124,8 +118,8 @@ func (s *StoreManager) GetMessage(mailbox, id string) (*Message, error) {
 		return nil, err
 	}
 	_ = r.Close()
-	header := makeMetadata(sm)
+	header := MakeMetadata(sm)
-	return &Message{Metadata: *header, env: env}, nil
+	return &Message{MessageMetadata: *header, env: env}, nil
 }
 
 // MarkSeen marks the message as having been read.
@@ -159,9 +153,9 @@ func (s *StoreManager) MailboxForAddress(mailbox string) (string, error) {
 	return s.AddrPolicy.ExtractMailbox(mailbox)
 }
 
-// makeMetadata populates Metadata from a storage.Message.
+// MakeMetadata populates Metadata from a storage.Message.
-func makeMetadata(m storage.Message) *Metadata {
+func MakeMetadata(m storage.Message) *event.MessageMetadata {
-	return &Metadata{
+	return &event.MessageMetadata{
 		Mailbox: m.Mailbox(),
 		ID:      m.ID(),
 		From:    m.From(),

pkg/message/manager_test.go

@@ -0,0 +1,38 @@
+package message_test
+
+import (
+	"testing"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/message"
+	"github.com/inbucket/inbucket/pkg/policy"
+	"github.com/inbucket/inbucket/pkg/test"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestManagerEmitsMessageStoredEvent(t *testing.T) {
+	extHost := extension.NewHost()
+	sm := &message.StoreManager{
+		AddrPolicy: &policy.Addressing{},
+		Store:      test.NewStore(),
+		ExtHost:    extHost,
+	}
+
+	listener := extHost.Events.AfterMessageStored.AsyncTestListener("manager", 1)
+
+	// Attempt to deliver a message to generate event.
+	if _, err := sm.Deliver(
+		&policy.Recipient{},
+		"from@example.com",
+		[]*policy.Recipient{},
+		"prefix",
+		[]byte("From: from@example.com\n\ntest email"),
+	); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := listener()
+	require.NoError(t, err)
+	assert.NotNil(t, got, "No event received, or it was nil")
+}

pkg/message/message.go

@@ -8,33 +8,22 @@ import (
 	"net/textproto"
 	"time"
 
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/jhillyerd/enmime"
 )
 
-// Metadata holds information about a message, but not the content.
-type Metadata struct {
-	Mailbox string
-	ID      string
-	From    *mail.Address
-	To      []*mail.Address
-	Date    time.Time
-	Subject string
-	Size    int64
-	Seen    bool
-}
-
 // Message holds both the metadata and content of a message.
 type Message struct {
-	Metadata
+	event.MessageMetadata
 	env *enmime.Envelope
 }
 
 // New constructs a new Message
-func New(m Metadata, e *enmime.Envelope) *Message {
+func New(m event.MessageMetadata, e *enmime.Envelope) *Message {
 	return &Message{
-		Metadata: m,
+		MessageMetadata: m,
-		env:      e,
+		env:             e,
 	}
 }
 
@@ -65,7 +54,7 @@ func (m *Message) Text() string {
 
 // Delivery is used to add a message to storage.
 type Delivery struct {
-	Meta   Metadata
+	Meta   event.MessageMetadata
 	Reader io.Reader
 }
 

pkg/msghub/hub.go

@@ -3,26 +3,19 @@ package msghub
 import (
 	"container/ring"
 	"context"
-	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/rs/zerolog/log"
 )
 
 // Length of msghub operation queue
 const opChanLen = 100
 
-// Message contains the basic header data for a message
-type Message struct {
-	Mailbox string
-	ID      string
-	From    string
-	To      []string
-	Subject string
-	Date    time.Time
-	Size    int64
-}
-
 // Listener receives the contents of the history buffer, followed by new messages
 type Listener interface {
-	Receive(msg Message) error
+	Receive(msg event.MessageMetadata) error
+	Delete(mailbox string, id string) error
 }
 
 // Hub relays messages on to its listeners
@@ -36,38 +29,51 @@ type Hub struct {
 // New constructs a new Hub which will cache historyLen messages in memory for playback to future
 // listeners.  A goroutine is created to handle incoming messages; it will run until the provided
 // context is canceled.
-func New(ctx context.Context, historyLen int) *Hub {
+func New(historyLen int, extHost *extension.Host) *Hub {
-	h := &Hub{
+	hub := &Hub{
 		history:   ring.New(historyLen),
 		listeners: make(map[Listener]struct{}),
 		opChan:    make(chan func(h *Hub), opChanLen),
 	}
 
-	go func() {
+	// Register an extension event listener for MessageStored.
-		for {
+	extHost.Events.AfterMessageStored.AddListener("msghub",
-			select {
+		func(msg event.MessageMetadata) {
-			case <-ctx.Done():
+			hub.Dispatch(msg)
-				// Shutdown
+		})
-				close(h.opChan)
-				return
-			case op := <-h.opChan:
-				op(h)
-			}
-		}
-	}()
 
-	return h
+	extHost.Events.AfterMessageDeleted.AddListener("msghub",
+		func(msg event.MessageMetadata) {
+			hub.Delete(msg.Mailbox, msg.ID)
+		})
+
+	return hub
+}
+
+// Start Hub processing loop.
+func (hub *Hub) Start(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			// Shutdown
+			close(hub.opChan)
+			return
+		case op := <-hub.opChan:
+			hub.runOp(op)
+		}
+	}
 }
 
 // Dispatch queues a message for broadcast by the hub.  The message will be placed into the
 // history buffer and then relayed to all registered listeners.
-func (hub *Hub) Dispatch(msg Message) {
+func (hub *Hub) Dispatch(msg event.MessageMetadata) {
 	hub.opChan <- func(h *Hub) {
 		if h.history != nil {
 			// Add to history buffer
 			h.history.Value = msg
 			h.history = h.history.Next()
-			// Deliver message to all listeners, removing listeners if they return an error
+
+			// Relay event to all listeners, removing listeners if they return an error.
 			for l := range h.listeners {
 				if err := l.Receive(msg); err != nil {
 					delete(h.listeners, l)
@@ -77,13 +83,44 @@ func (hub *Hub) Dispatch(msg Message) {
 	}
 }
 
+// Delete removes the message from the history buffer and instructs listeners to do the same.
+func (hub *Hub) Delete(mailbox string, id string) {
+	hub.opChan <- func(h *Hub) {
+		if h.history == nil {
+			return
+		}
+
+		// Locate and remove history entry.
+		p := h.history
+		end := p
+		for {
+			if next, ok := p.Next().Value.(event.MessageMetadata); ok {
+				if mailbox == next.Mailbox && id == next.ID {
+					p.Next().Value = nil
+					break
+				}
+			}
+			if p = p.Next(); p == end {
+				break
+			}
+		}
+
+		// Relay event to all listeners, removing listeners if they return an error.
+		for l := range h.listeners {
+			if err := l.Delete(mailbox, id); err != nil {
+				delete(h.listeners, l)
+			}
+		}
+	}
+}
+
 // AddListener registers a listener to receive broadcasted messages.
 func (hub *Hub) AddListener(l Listener) {
 	hub.opChan <- func(h *Hub) {
 		// Playback log
 		h.history.Do(func(v interface{}) {
 			if v != nil {
-				l.Receive(v.(Message))
+				l.Receive(v.(event.MessageMetadata))
 			}
 		})
 
@@ -108,3 +145,17 @@ func (hub *Hub) Sync() {
 	}
 	<-done
 }
+
+func (hub *Hub) runOp(op func(*Hub)) {
+	defer func() {
+		if r := recover(); r != nil {
+			if err, ok := r.(error); ok {
+				log.Error().Str("module", "msghub").Err(err).Msg("Operation panicked")
+			} else {
+				log.Error().Str("module", "msghub").Err(err).Msgf("Operation panicked: %s", r)
+			}
+		}
+	}()
+
+	op(hub)
+}

pkg/msghub/hub_test.go

@@ -3,15 +3,23 @@ package msghub
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"testing"
 	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // testListener implements the Listener interface, mock for unit tests
 type testListener struct {
-	messages     []*Message // received messages
+	messages   []*event.MessageMetadata // received messages
-	wantMessages int        // how many messages this listener wants to receive
+	deletes    []string                 // received deletes
-	errorAfter   int        // when != 0, messages until Receive() begins returning error
+	wantEvents int                      // how many events this listener wants to receive
+	errorAfter int                      // when != 0, event count until Receive() begins returning error
+	gotEvents  int
 
 	done     chan struct{} // closed once we have received wantMessages
 	overflow chan struct{} // closed if we receive wantMessages+1
@@ -19,10 +27,11 @@ type testListener struct {
 
 func newTestListener(want int) *testListener {
 	l := &testListener{
-		messages:     make([]*Message, 0, want*2),
+		messages:   make([]*event.MessageMetadata, 0, want*2),
-		wantMessages: want,
+		deletes:    make([]string, 0, want*2),
-		done:         make(chan struct{}),
+		wantEvents: want,
-		overflow:     make(chan struct{}),
+		done:       make(chan struct{}),
+		overflow:   make(chan struct{}),
 	}
 	if want == 0 {
 		close(l.done)
@@ -32,29 +41,34 @@ func newTestListener(want int) *testListener {
 
 // Receive a Message, store it in the messages slice, close applicable channels, and return an error
 // if instructed
-func (l *testListener) Receive(msg Message) error {
+func (l *testListener) Receive(msg event.MessageMetadata) error {
+	l.gotEvents++
 	l.messages = append(l.messages, &msg)
-	if len(l.messages) == l.wantMessages {
+	if l.gotEvents == l.wantEvents {
 		close(l.done)
 	}
-	if len(l.messages) == l.wantMessages+1 {
+	if l.gotEvents == l.wantEvents+1 {
 		close(l.overflow)
 	}
-	if l.errorAfter > 0 && len(l.messages) > l.errorAfter {
+	if l.errorAfter > 0 && l.gotEvents > l.errorAfter {
 		return fmt.Errorf("Too many messages")
 	}
 	return nil
 }
 
+func (l *testListener) Delete(mailbox string, id string) error {
+	l.gotEvents++
+	l.deletes = append(l.deletes, mailbox+"/"+id)
+	return nil
+}
+
 // String formats the got vs wanted message counts
 func (l *testListener) String() string {
-	return fmt.Sprintf("got %v messages, wanted %v", len(l.messages), l.wantMessages)
+	return fmt.Sprintf("got %v messages, wanted %v", len(l.messages), l.wantEvents)
 }
 
 func TestHubNew(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
+	hub := New(5, extension.NewHost())
-	defer cancel()
-	hub := New(ctx, 5)
 	if hub == nil {
 		t.Fatal("New() == nil, expected a new Hub")
 	}
@@ -63,30 +77,33 @@ func TestHubNew(t *testing.T) {
 func TestHubZeroLen(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 0)
+	hub := New(0, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 	for i := 0; i < 100; i++ {
 		hub.Dispatch(m)
 	}
-	// Just making sure Hub doesn't panic
+	// Ensures Hub doesn't panic
 }
 
 func TestHubZeroListeners(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 	for i := 0; i < 100; i++ {
 		hub.Dispatch(m)
 	}
-	// Just making sure Hub doesn't panic
+	// Ensures Hub doesn't panic
 }
 
 func TestHubOneListener(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 	l := newTestListener(1)
 
 	hub.AddListener(l)
@@ -103,8 +120,9 @@ func TestHubOneListener(t *testing.T) {
 func TestHubRemoveListener(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 	l := newTestListener(1)
 
 	hub.AddListener(l)
@@ -125,8 +143,9 @@ func TestHubRemoveListener(t *testing.T) {
 func TestHubRemoveListenerOnError(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 
 	// error after 1 means listener should receive 2 messages before being removed
 	l := newTestListener(2)
@@ -151,14 +170,15 @@ func TestHubRemoveListenerOnError(t *testing.T) {
 func TestHubHistoryReplay(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 100)
+	hub := New(100, extension.NewHost())
+	go hub.Start(ctx)
 	l1 := newTestListener(3)
 	hub.AddListener(l1)
 
 	// Broadcast 3 messages with no listeners
-	msgs := make([]Message, 3)
+	msgs := make([]event.MessageMetadata, 3)
 	for i := 0; i < len(msgs); i++ {
-		msgs[i] = Message{
+		msgs[i] = event.MessageMetadata{
 			Subject: fmt.Sprintf("subj %v", i),
 		}
 		hub.Dispatch(msgs[i])
@@ -191,17 +211,67 @@ func TestHubHistoryReplay(t *testing.T) {
 	}
 }
 
+func TestHubHistoryDelete(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	hub := New(100, extension.NewHost())
+	go hub.Start(ctx)
+	l1 := newTestListener(3)
+	hub.AddListener(l1)
+
+	// Broadcast 3 messages with no listeners
+	msgs := make([]event.MessageMetadata, 3)
+	for i := 0; i < len(msgs); i++ {
+		msgs[i] = event.MessageMetadata{
+			Mailbox: "hub",
+			ID:      strconv.Itoa(i),
+			Subject: fmt.Sprintf("subj %v", i),
+		}
+		hub.Dispatch(msgs[i])
+	}
+
+	// Wait for messages (live)
+	select {
+	case <-l1.done:
+	case <-time.After(time.Second):
+		t.Fatal("Timeout:", l1)
+	}
+
+	hub.Delete("hub", "1") // Delete a message
+	hub.Delete("zzz", "0") // Attempt to delete non-existent mailbox message
+
+	// Add a new listener, waits for 2 messages
+	l2 := newTestListener(2)
+	hub.AddListener(l2)
+
+	// Wait for messages (history)
+	select {
+	case <-l2.done:
+	case <-time.After(time.Second):
+		t.Fatal("Timeout:", l2)
+	}
+
+	want := []string{"subj 0", "subj 2"}
+	for i := 0; i < len(want); i++ {
+		got := l2.messages[i].Subject
+		if got != want[i] {
+			t.Errorf("msg[%v].Subject == %q, want %q", i, got, want[i])
+		}
+	}
+}
+
 func TestHubHistoryReplayWrap(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
+	go hub.Start(ctx)
 	l1 := newTestListener(20)
 	hub.AddListener(l1)
 
 	// Broadcast more messages than the hub can hold
-	msgs := make([]Message, 20)
+	msgs := make([]event.MessageMetadata, 20)
 	for i := 0; i < len(msgs); i++ {
-		msgs[i] = Message{
+		msgs[i] = event.MessageMetadata{
 			Subject: fmt.Sprintf("subj %v", i),
 		}
 		hub.Dispatch(msgs[i])
@@ -234,10 +304,64 @@ func TestHubHistoryReplayWrap(t *testing.T) {
 	}
 }
 
+func TestHubHistoryReplayWrapAfterDelete(t *testing.T) {
+	bufferSize := 5
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	hub := New(bufferSize, extension.NewHost())
+	go hub.Start(ctx)
+
+	waitForMessages := func(n int) {
+		l := newTestListener(n)
+		hub.AddListener(l)
+
+		select {
+		case <-l.done:
+		case <-time.After(time.Second):
+			t.Fatal("Timeout:", l)
+		}
+	}
+
+	// Broadcast more messages than the hub can hold.
+	msgs := make([]event.MessageMetadata, 10)
+	for i := 0; i < len(msgs); i++ {
+		msgs[i] = event.MessageMetadata{
+			Mailbox: "first",
+			ID:      strconv.Itoa(i),
+			Subject: fmt.Sprintf("subj %v", i),
+		}
+		hub.Dispatch(msgs[i])
+	}
+	waitForMessages(bufferSize)
+
+	// Buffer must be configured size.
+	require.Equal(t, bufferSize, hub.history.Len())
+
+	// Delete a message still present in buffer.
+	hub.Delete("first", "7")
+
+	// Broadcast another set of messages.
+	for i := 0; i < len(msgs); i++ {
+		msgs[i] = event.MessageMetadata{
+			Mailbox: "second",
+			ID:      strconv.Itoa(i),
+			Subject: fmt.Sprintf("subj %v", i),
+		}
+		hub.Dispatch(msgs[i])
+	}
+	waitForMessages(bufferSize)
+
+	// Ensure the buffer did not shrink after delete.
+	got := hub.history.Len()
+	assert.Equal(t, bufferSize, got, "got buffer size %d, wanted %d", got, bufferSize)
+}
+
 func TestHubContextCancel(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
-	hub := New(ctx, 5)
+	hub := New(5, extension.NewHost())
-	m := Message{}
+	go hub.Start(ctx)
+	m := event.MessageMetadata{}
 	l := newTestListener(1)
 
 	hub.AddListener(l)

pkg/policy/address.go

@@ -3,6 +3,7 @@ package policy
 import (
 	"bytes"
 	"fmt"
+	"net"
 	"net/mail"
 	"strings"
 
@@ -17,44 +18,41 @@ type Addressing struct {
 
 // ExtractMailbox extracts the mailbox name from a partial email address.
 func (a *Addressing) ExtractMailbox(address string) (string, error) {
+	if a.Config.MailboxNaming == config.DomainNaming {
+		return extractDomainMailbox(address)
+	}
+
 	local, domain, err := parseEmailAddress(address)
 	if err != nil {
 		return "", err
 	}
+
 	local, err = parseMailboxName(local)
 	if err != nil {
 		return "", err
 	}
+
 	if a.Config.MailboxNaming == config.LocalNaming {
 		return local, nil
 	}
-	if a.Config.MailboxNaming == config.DomainNaming {
+
-		// If no domain is specified, assume this is being
-		// used for mailbox lookup via the API.
-		if domain == "" {
-			if ValidateDomainPart(local) == false {
-				return "", fmt.Errorf("Domain part %q in %q failed validation", local, address)
-			}
-			return local, nil
-		}
-		if ValidateDomainPart(domain) == false {
-			return "", fmt.Errorf("Domain part %q in %q failed validation", domain, address)
-		}
-		return domain, nil
-	}
 	if a.Config.MailboxNaming != config.FullNaming {
 		return "", fmt.Errorf("Unknown MailboxNaming value: %v", a.Config.MailboxNaming)
 	}
+
 	if domain == "" {
 		return local, nil
 	}
+
 	if !ValidateDomainPart(domain) {
 		return "", fmt.Errorf("Domain part %q in %q failed validation", domain, address)
 	}
+
 	return local + "@" + domain, nil
 }
 
-// NewRecipient parses an address into a Recipient.
+// NewRecipient parses an address into a Recipient. This is used for parsing RCPT TO arguments,
+// not To headers.
 func (a *Addressing) NewRecipient(address string) (*Recipient, error) {
 	local, domain, err := ParseEmailAddress(address)
 	if err != nil {
@@ -64,12 +62,8 @@ func (a *Addressing) NewRecipient(address string) (*Recipient, error) {
 	if err != nil {
 		return nil, err
 	}
-	ar, err := mail.ParseAddress(address)
-	if err != nil {
-		return nil, err
-	}
 	return &Recipient{
-		Address:    *ar,
+		Address:    mail.Address{Address: address},
 		addrPolicy: a,
 		LocalPart:  local,
 		Domain:     domain,
@@ -122,13 +116,24 @@ func ParseEmailAddress(address string) (local string, domain string, err error)
 // ValidateDomainPart returns true if the domain part complies to RFC3696, RFC1035. Used by
 // ParseEmailAddress().
 func ValidateDomainPart(domain string) bool {
-	if len(domain) == 0 {
+	ln := len(domain)
+	if ln == 0 {
 		return false
 	}
-	if len(domain) > 255 {
+	if ln > 255 {
 		return false
 	}
-	if domain[len(domain)-1] != '.' {
+	if ln >= 4 && domain[0] == '[' && domain[ln-1] == ']' {
+		// Bracketed domains must contain an IP address.
+		s := 1
+		if strings.HasPrefix(domain[1:], "IPv6:") {
+			s = 6
+		}
+		ip := net.ParseIP(domain[s : ln-1])
+		return ip != nil
+	}
+
+	if domain[ln-1] != '.' {
 		domain += "."
 	}
 	prev := '.'
@@ -168,6 +173,40 @@ func ValidateDomainPart(domain string) bool {
 	return true
 }
 
+// Extracts the mailbox name when domain addressing is enabled.
+func extractDomainMailbox(address string) (string, error) {
+	var local, domain string
+	var err error
+
+	if address != "" && address[0] == '[' && address[len(address)-1] == ']' {
+		// Likely an IP address in brackets, treat as domain only.
+		domain = address
+	} else {
+		local, domain, err = parseEmailAddress(address)
+		if err != nil {
+			return "", err
+		}
+	}
+
+	if local != "" {
+		local, err = parseMailboxName(local)
+		if err != nil {
+			return "", err
+		}
+	}
+
+	// If no @domain is specified, assume this is being used for mailbox lookup via the API.
+	if domain == "" {
+		domain = local
+	}
+
+	if ValidateDomainPart(domain) == false {
+		return "", fmt.Errorf("Domain part %q in %q failed validation", domain, address)
+	}
+
+	return domain, nil
+}
+
 // parseEmailAddress unescapes an email address, and splits the local part from the domain part.  An
 // error is returned if the local part fails validation following the guidelines in RFC3696. The
 // domain part is optional and not validated.
@@ -178,12 +217,23 @@ func parseEmailAddress(address string) (local string, domain string, err error)
 	if len(address) > 320 {
 		return "", "", fmt.Errorf("address exceeds 320 characters")
 	}
+
+	// Remove forward-path routes.
 	if address[0] == '@' {
-		return "", "", fmt.Errorf("address cannot start with @ symbol")
+		end := strings.IndexRune(address, ':')
+		if end == -1 {
+			return "", "", fmt.Errorf("missing terminating ':' in route specification")
+		}
+		address = address[end+1:]
+		if address == "" {
+			return "", "", fmt.Errorf("Address empty after removing route specification")
+		}
 	}
+
 	if address[0] == '.' {
 		return "", "", fmt.Errorf("address cannot start with a period")
 	}
+
 	// Loop over address parsing out local part.
 	buf := new(bytes.Buffer)
 	prev := byte('.')

pkg/policy/address_test.go

@@ -259,6 +259,30 @@ func TestExtractMailboxValid(t *testing.T) {
 			full:   "chars|}~@example.co.uk",
 			domain: "example.co.uk",
 		},
+		{
+			input:  "@host:user+label@domain.com",
+			local:  "user",
+			full:   "user@domain.com",
+			domain: "domain.com",
+		},
+		{
+			input:  "@a.com,@b.com:user+label@domain.com",
+			local:  "user",
+			full:   "user@domain.com",
+			domain: "domain.com",
+		},
+		{
+			input:  "u@[127.0.0.1]",
+			local:  "u",
+			full:   "u@[127.0.0.1]",
+			domain: "[127.0.0.1]",
+		},
+		{
+			input:  "u@[IPv6:2001:db8:aaaa:1::100]",
+			local:  "u",
+			full:   "u@[IPv6:2001:db8:aaaa:1::100]",
+			domain: "[IPv6:2001:db8:aaaa:1::100]",
+		},
 	}
 	for _, tc := range testTable {
 		if result, err := localPolicy.ExtractMailbox(tc.input); err != nil {
@@ -285,10 +309,42 @@ func TestExtractMailboxValid(t *testing.T) {
 	}
 }
 
+// Test special cases with domain addressing mode.
+func TestExtractDomainMailboxValid(t *testing.T) {
+	domainPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.DomainNaming}}
+
+	tests := map[string]struct {
+		input  string // Input to test
+		domain string // Expected output when mailbox naming = domain
+	}{
+		"ipv4": {
+			input:  "[127.0.0.1]",
+			domain: "[127.0.0.1]",
+		},
+		"medium ipv6": {
+			input:  "[IPv6:2001:db8:aaaa:1::100]",
+			domain: "[IPv6:2001:db8:aaaa:1::100]",
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			if result, err := domainPolicy.ExtractMailbox(tc.input); tc.domain != "" && err != nil {
+				t.Errorf("Error while parsing with domain naming %q: %v", tc.input, err)
+			} else {
+				if result != tc.domain {
+					t.Errorf("Parsing %q, expected %q, got %q", tc.input, tc.domain, result)
+				}
+			}
+		})
+	}
+}
+
 func TestExtractMailboxInvalid(t *testing.T) {
 	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.LocalNaming}}
 	fullPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.FullNaming}}
 	domainPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.DomainNaming}}
+
 	// Test local mailbox naming policy.
 	localInvalidTable := []struct {
 		input, msg string
@@ -303,6 +359,7 @@ func TestExtractMailboxInvalid(t *testing.T) {
 			t.Errorf("Didn't get an error while parsing in local mode %q: %v", tt.input, tt.msg)
 		}
 	}
+
 	// Test full mailbox naming policy.
 	fullInvalidTable := []struct {
 		input, msg string
@@ -318,6 +375,7 @@ func TestExtractMailboxInvalid(t *testing.T) {
 			t.Errorf("Didn't get an error while parsing in full mode %q: %v", tt.input, tt.msg)
 		}
 	}
+
 	// Test domain mailbox naming policy.
 	domainInvalidTable := []struct {
 		input, msg string
@@ -365,6 +423,10 @@ func TestValidateDomain(t *testing.T) {
 		{strings.Repeat("a", 256), false, "Max domain length is 255"},
 		{strings.Repeat("a", 63) + ".com", true, "Should allow 63 char domain label"},
 		{strings.Repeat("a", 64) + ".com", false, "Max domain label length is 63"},
+		{"[0.0.0.0]", true, "Single digit octet IP addr is valid"},
+		{"[123.123.123.123]", true, "Multiple digit octet IP addr is valid"},
+		{"[IPv6:2001:0db8:aaaa:0001:0000:0000:0000:0200]", true, "Full IPv6 addr is valid"},
+		{"[IPv6:::1]", true, "Abbr IPv6 addr is valid"},
 	}
 	for _, tt := range testTable {
 		if policy.ValidateDomainPart(tt.input) != tt.expect {
@@ -419,6 +481,9 @@ func TestValidateLocal(t *testing.T) {
 		{"$A12345", true, "RFC3696 test case should be valid"},
 		{"!def!xyz%abc", true, "RFC3696 test case should be valid"},
 		{"_somename", true, "RFC3696 test case should be valid"},
+		{"@host:mailbox", true, "Forward-path routes are valid"},
+		{"@a.com,@b.com:mailbox", true, "Multi-hop forward-path routes are valid"},
+		{"@a.com,mailbox", false, "Unterminated forward-path routes are invalid"},
 	}
 	for _, tt := range testTable {
 		_, _, err := policy.ParseEmailAddress(tt.input + "@domain.com")
@@ -430,3 +495,33 @@ func TestValidateLocal(t *testing.T) {
 		}
 	}
 }
+
+// TestRecipientAddress verifies the Recipient.Address values returned by Addressing.NewRecipient.
+// This function parses a RCPT TO path, not a To header. See rfc5321#section-4.1.2
+func TestRecipientAddress(t *testing.T) {
+	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.LocalNaming}}
+
+	tests := map[string]string{
+		"common":          "user@example.com",
+		"with label":      "user+mailbox@example.com",
+		"special chars":   "a!#$%&'*+-/=?^_`{|}~@example.com",
+		"ipv4":            "user@[127.0.0.1]",
+		"ipv6":            "user@[IPv6:::1]",
+		"route host":      "@host:user@example.com",
+		"route domain":    "@route.com:user@example.com",
+		"multi-hop route": "@first.com,@second.com:user@example.com",
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			r, err := localPolicy.NewRecipient(tc)
+			if err != nil {
+				t.Fatalf("Parse of %q failed: %v", tc, err)
+			}
+
+			if got, want := r.Address.Address, tc; got != want {
+				t.Errorf("Got Address: %q, want: %q", got, want)
+			}
+		})
+	}
+}

pkg/rest/apiv1_controller_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/test"
 	"github.com/jhillyerd/enmime"
@@ -67,7 +68,7 @@ func TestRestMailboxList(t *testing.T) {
 	// Test JSON message headers
 	tzPDT := time.FixedZone("PDT", -7*3600)
 	tzPST := time.FixedZone("PST", -8*3600)
-	meta1 := message.Metadata{
+	meta1 := event.MessageMetadata{
 		Mailbox: "good",
 		ID:      "0001",
 		From:    &mail.Address{Name: "", Address: "from1@host"},
@@ -75,7 +76,7 @@ func TestRestMailboxList(t *testing.T) {
 		Subject: "subject 1",
 		Date:    time.Date(2012, 2, 1, 10, 11, 12, 253, tzPST),
 	}
-	meta2 := message.Metadata{
+	meta2 := event.MessageMetadata{
 		Mailbox: "good",
 		ID:      "0002",
 		From:    &mail.Address{Name: "", Address: "from2@host"},
@@ -83,8 +84,8 @@ func TestRestMailboxList(t *testing.T) {
 		Subject: "subject 2",
 		Date:    time.Date(2012, 7, 1, 10, 11, 12, 253, tzPDT),
 	}
-	mm.AddMessage("good", &message.Message{Metadata: meta1})
+	mm.AddMessage("good", &message.Message{MessageMetadata: meta1})
-	mm.AddMessage("good", &message.Message{Metadata: meta2})
+	mm.AddMessage("good", &message.Message{MessageMetadata: meta2})
 
 	// Check return code
 	w, err = testRestGet("http://localhost/api/v1/mailbox/good")
@@ -178,7 +179,7 @@ func TestRestMessage(t *testing.T) {
 	// Test JSON message headers
 	tzPST := time.FixedZone("PST", -8*3600)
 	msg1 := message.New(
-		message.Metadata{
+		event.MessageMetadata{
 			Mailbox: "good",
 			ID:      "0001",
 			From:    &mail.Address{Name: "", Address: "from1@host"},
@@ -254,7 +255,7 @@ func TestRestMarkSeen(t *testing.T) {
 	// Create some messages.
 	tzPDT := time.FixedZone("PDT", -7*3600)
 	tzPST := time.FixedZone("PST", -8*3600)
-	meta1 := message.Metadata{
+	meta1 := event.MessageMetadata{
 		Mailbox: "good",
 		ID:      "0001",
 		From:    &mail.Address{Name: "", Address: "from1@host"},
@@ -262,7 +263,7 @@ func TestRestMarkSeen(t *testing.T) {
 		Subject: "subject 1",
 		Date:    time.Date(2012, 2, 1, 10, 11, 12, 253, tzPST),
 	}
-	meta2 := message.Metadata{
+	meta2 := event.MessageMetadata{
 		Mailbox: "good",
 		ID:      "0002",
 		From:    &mail.Address{Name: "", Address: "from2@host"},
@@ -270,8 +271,8 @@ func TestRestMarkSeen(t *testing.T) {
 		Subject: "subject 2",
 		Date:    time.Date(2012, 7, 1, 10, 11, 12, 253, tzPDT),
 	}
-	mm.AddMessage("good", &message.Message{Metadata: meta1})
+	mm.AddMessage("good", &message.Message{MessageMetadata: meta1})
-	mm.AddMessage("good", &message.Message{Metadata: meta2})
+	mm.AddMessage("good", &message.Message{MessageMetadata: meta2})
 	// Mark one read.
 	w, err := testRestPatch("http://localhost/api/v1/mailbox/good/0002", `{"seen":true}`)
 	expectCode := 200

pkg/rest/model/apiv1_model.go

@@ -4,7 +4,7 @@ import (
 	"time"
 )
 
-// JSONMessageHeaderV1 contains the basic header data for a message
+// JSONMessageHeaderV1 contains the basic header data for a message.
 type JSONMessageHeaderV1 struct {
 	Mailbox     string    `json:"mailbox"`
 	ID          string    `json:"id"`
@@ -17,7 +17,7 @@ type JSONMessageHeaderV1 struct {
 	Seen        bool      `json:"seen"`
 }
 
-// JSONMessageV1 contains the same data as the header plus a JSONMessageBody
+// JSONMessageV1 contains the same data as the header plus a JSONMessageBody.
 type JSONMessageV1 struct {
 	Mailbox     string                     `json:"mailbox"`
 	ID          string                     `json:"id"`
@@ -33,7 +33,7 @@ type JSONMessageV1 struct {
 	Attachments []*JSONMessageAttachmentV1 `json:"attachments"`
 }
 
-// JSONMessageAttachmentV1 contains information about a MIME attachment
+// JSONMessageAttachmentV1 contains information about a MIME attachment.
 type JSONMessageAttachmentV1 struct {
 	FileName     string `json:"filename"`
 	ContentType  string `json:"content-type"`
@@ -42,7 +42,7 @@ type JSONMessageAttachmentV1 struct {
 	MD5          string `json:"md5"`
 }
 
-// JSONMessageBodyV1 contains the Text and HTML versions of the message body
+// JSONMessageBodyV1 contains the Text and HTML versions of the message body.
 type JSONMessageBodyV1 struct {
 	Text string `json:"text"`
 	HTML string `json:"html"`

pkg/rest/model/apiv2_model.go

@@ -0,0 +1,15 @@
+package model
+
+// JSONMessageIDV2 uniquely identifies a message.
+type JSONMessageIDV2 struct {
+	Mailbox string `json:"mailbox"`
+	ID      string `json:"id"`
+}
+
+// JSONMonitorEventV2 contains events for the Inbucket mailbox and monitor tabs.
+type JSONMonitorEventV2 struct {
+	// Event variant: `message-deleted`, `message-stored`.
+	Variant    string               `json:"variant"`
+	Identifier *JSONMessageIDV2     `json:"identifier"`
+	Header     *JSONMessageHeaderV1 `json:"header"`
+}

pkg/rest/routes.go

@@ -22,4 +22,10 @@ func SetupRoutes(r *mux.Router) {
 		web.Handler(MonitorAllMessagesV1)).Name("MonitorAllMessagesV1").Methods("GET")
 	r.Path("/v1/monitor/messages/{name}").Handler(
 		web.Handler(MonitorMailboxMessagesV1)).Name("MonitorMailboxMessagesV1").Methods("GET")
+
+	// API v2
+	r.Path("/v2/monitor/messages").Handler(
+		web.Handler(MonitorAllMessagesV2)).Name("MonitorAllMessagesV2").Methods("GET")
+	r.Path("/v2/monitor/messages/{name}").Handler(
+		web.Handler(MonitorMailboxMessagesV2)).Name("MonitorMailboxMessagesV2").Methods("GET")
 }

pkg/rest/socketv1_controller.go

@@ -5,71 +5,79 @@ import (
 	"time"
 
 	"github.com/gorilla/websocket"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/msghub"
 	"github.com/inbucket/inbucket/pkg/rest/model"
 	"github.com/inbucket/inbucket/pkg/server/web"
+	"github.com/inbucket/inbucket/pkg/stringutil"
 	"github.com/rs/zerolog/log"
 )
 
 const (
 	// Time allowed to write a message to the peer.
-	writeWait = 10 * time.Second
+	writeWaitV1 = 10 * time.Second
 
 	// Send pings to peer with this period. Must be less than pongWait.
-	pingPeriod = (pongWait * 9) / 10
+	pingPeriodV1 = (pongWaitV1 * 9) / 10
 
 	// Time allowed to read the next pong message from the peer.
-	pongWait = 60 * time.Second
+	pongWaitV1 = 60 * time.Second
 
 	// Maximum message size allowed from peer.
-	maxMessageSize = 512
+	maxMessageSizeV1 = 512
 )
 
 // options for gorilla connection upgrader
-var upgrader = websocket.Upgrader{
+var upgraderV1 = websocket.Upgrader{
 	ReadBufferSize:  1024,
 	WriteBufferSize: 1024,
 }
 
-// msgListener handles messages from the msghub
+// msgListenerV1 handles messages from the msghub
-type msgListener struct {
+type msgListenerV1 struct {
-	hub     *msghub.Hub         // Global message hub
+	hub     *msghub.Hub                // Global message hub
-	c       chan msghub.Message // Queue of messages from Receive()
+	c       chan event.MessageMetadata // Queue of messages from Receive()
-	mailbox string              // Name of mailbox to monitor, "" == all mailboxes
+	mailbox string                     // Name of mailbox to monitor, "" == all mailboxes
 }
 
-// newMsgListener creates a listener and registers it.  Optional mailbox parameter will restrict
+// newMsgListenerV1 creates a listener and registers it.  Optional mailbox parameter will restrict
 // messages sent to WebSocket to that mailbox only.
-func newMsgListener(hub *msghub.Hub, mailbox string) *msgListener {
+func newMsgListenerV1(hub *msghub.Hub, mailbox string) *msgListenerV1 {
-	ml := &msgListener{
+	ml := &msgListenerV1{
 		hub:     hub,
-		c:       make(chan msghub.Message, 100),
+		c:       make(chan event.MessageMetadata, 100),
 		mailbox: mailbox,
 	}
 	hub.AddListener(ml)
 	return ml
 }
 
-// Receive handles an incoming message
+// Receive handles an incoming message.
-func (ml *msgListener) Receive(msg msghub.Message) error {
+func (ml *msgListenerV1) Receive(msg event.MessageMetadata) error {
 	if ml.mailbox != "" && ml.mailbox != msg.Mailbox {
-		// Did not match mailbox name
+		// Did not match the watched mailbox name.
 		return nil
 	}
 	ml.c <- msg
 	return nil
 }
 
+// Delete handles a deleted message.
+func (ml *msgListenerV1) Delete(mailbox string, id string) error {
+	// Deletes are ignored in socketv1 API.
+	return nil
+}
+
 // WSReader makes sure the websocket client is still connected, discards any messages from client
-func (ml *msgListener) WSReader(conn *websocket.Conn) {
+func (ml *msgListenerV1) WSReader(conn *websocket.Conn) {
 	slog := log.With().Str("module", "rest").Str("proto", "WebSocket").
 		Str("remote", conn.RemoteAddr().String()).Logger()
 	defer ml.Close()
-	conn.SetReadLimit(maxMessageSize)
+	conn.SetReadLimit(maxMessageSizeV1)
-	conn.SetReadDeadline(time.Now().Add(pongWait))
+	conn.SetReadDeadline(time.Now().Add(pongWaitV1))
 	conn.SetPongHandler(func(string) error {
 		slog.Debug().Msg("Got pong")
-		conn.SetReadDeadline(time.Now().Add(pongWait))
+		conn.SetReadDeadline(time.Now().Add(pongWaitV1))
 		return nil
 	})
 
@@ -92,8 +100,8 @@ func (ml *msgListener) WSReader(conn *websocket.Conn) {
 }
 
 // WSWriter makes sure the websocket client is still connected
-func (ml *msgListener) WSWriter(conn *websocket.Conn) {
+func (ml *msgListenerV1) WSWriter(conn *websocket.Conn) {
-	ticker := time.NewTicker(pingPeriod)
+	ticker := time.NewTicker(pingPeriodV1)
 	defer func() {
 		ticker.Stop()
 		ml.Close()
@@ -103,29 +111,19 @@ func (ml *msgListener) WSWriter(conn *websocket.Conn) {
 	for {
 		select {
 		case msg, ok := <-ml.c:
-			conn.SetWriteDeadline(time.Now().Add(writeWait))
+			conn.SetWriteDeadline(time.Now().Add(writeWaitV1))
 			if !ok {
 				// msgListener closed, exit
 				conn.WriteMessage(websocket.CloseMessage, []byte{})
 				return
 			}
-			header := &model.JSONMessageHeaderV1{
+			if conn.WriteJSON(metadataToHeader(&msg)) != nil {
-				Mailbox:     msg.Mailbox,
-				ID:          msg.ID,
-				From:        msg.From,
-				To:          msg.To,
-				Subject:     msg.Subject,
-				Date:        msg.Date,
-				PosixMillis: msg.Date.UnixNano() / 1000000,
-				Size:        msg.Size,
-			}
-			if conn.WriteJSON(header) != nil {
 				// Write failed
 				return
 			}
 		case <-ticker.C:
 			// Send ping
-			conn.SetWriteDeadline(time.Now().Add(writeWait))
+			conn.SetWriteDeadline(time.Now().Add(writeWaitV1))
 			if conn.WriteMessage(websocket.PingMessage, []byte{}) != nil {
 				// Write error
 				return
@@ -137,7 +135,7 @@ func (ml *msgListener) WSWriter(conn *websocket.Conn) {
 }
 
 // Close removes the listener registration
-func (ml *msgListener) Close() {
+func (ml *msgListenerV1) Close() {
 	select {
 	case <-ml.c:
 		// Already closed
@@ -152,7 +150,7 @@ func (ml *msgListener) Close() {
 func MonitorAllMessagesV1(
 	w http.ResponseWriter, req *http.Request, ctx *web.Context) (err error) {
 	// Upgrade to Websocket.
-	conn, err := upgrader.Upgrade(w, req, nil)
+	conn, err := upgraderV1.Upgrade(w, req, nil)
 	if err != nil {
 		return err
 	}
@@ -164,7 +162,7 @@ func MonitorAllMessagesV1(
 	log.Debug().Str("module", "rest").Str("proto", "WebSocket").
 		Str("remote", conn.RemoteAddr().String()).Msg("Upgraded to WebSocket")
 	// Create, register listener; then interact with conn.
-	ml := newMsgListener(ctx.MsgHub, "")
+	ml := newMsgListenerV1(ctx.MsgHub, "")
 	go ml.WSWriter(conn)
 	ml.WSReader(conn)
 	return nil
@@ -179,7 +177,7 @@ func MonitorMailboxMessagesV1(
 		return err
 	}
 	// Upgrade to Websocket.
-	conn, err := upgrader.Upgrade(w, req, nil)
+	conn, err := upgraderV1.Upgrade(w, req, nil)
 	if err != nil {
 		return err
 	}
@@ -191,8 +189,21 @@ func MonitorMailboxMessagesV1(
 	log.Debug().Str("module", "rest").Str("proto", "WebSocket").
 		Str("remote", conn.RemoteAddr().String()).Msg("Upgraded to WebSocket")
 	// Create, register listener; then interact with conn.
-	ml := newMsgListener(ctx.MsgHub, name)
+	ml := newMsgListenerV1(ctx.MsgHub, name)
 	go ml.WSWriter(conn)
 	ml.WSReader(conn)
 	return nil
 }
+
+func metadataToHeader(msg *event.MessageMetadata) *model.JSONMessageHeaderV1 {
+	return &model.JSONMessageHeaderV1{
+		Mailbox:     msg.Mailbox,
+		ID:          msg.ID,
+		From:        stringutil.StringAddress(msg.From),
+		To:          stringutil.StringAddressList(msg.To),
+		Subject:     msg.Subject,
+		Date:        msg.Date,
+		PosixMillis: msg.Date.UnixNano() / 1000000,
+		Size:        msg.Size,
+	}
+}

pkg/rest/socketv2_controller.go

@@ -0,0 +1,214 @@
+package rest
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/inbucket/inbucket/pkg/extension/event"
+	"github.com/inbucket/inbucket/pkg/msghub"
+	"github.com/inbucket/inbucket/pkg/rest/model"
+	"github.com/inbucket/inbucket/pkg/server/web"
+	"github.com/rs/zerolog/log"
+)
+
+const (
+	// Time allowed to write a message to the peer.
+	writeWaitV2 = 10 * time.Second
+
+	// Send pings to peer with this period. Must be less than pongWait.
+	pingPeriodV2 = (pongWaitV2 * 9) / 10
+
+	// Time allowed to read the next pong message from the peer.
+	pongWaitV2 = 60 * time.Second
+
+	// Maximum message size allowed from peer.
+	maxMessageSizeV2 = 512
+)
+
+// options for gorilla connection upgrader
+var upgraderV2 = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+// msgListenerV2 handles messages from the msghub
+type msgListenerV2 struct {
+	hub     *msghub.Hub                    // Global message hub.
+	c       chan *model.JSONMonitorEventV2 // Queue of incoming events.
+	mailbox string                         // Name of mailbox to monitor, "" == all mailboxes.
+}
+
+// newMsgListenerV2 creates a listener and registers it.  Optional mailbox parameter will restrict
+// messages sent to WebSocket to that mailbox only.
+func newMsgListenerV2(hub *msghub.Hub, mailbox string) *msgListenerV2 {
+	ml := &msgListenerV2{
+		hub:     hub,
+		c:       make(chan *model.JSONMonitorEventV2, 100),
+		mailbox: mailbox,
+	}
+	hub.AddListener(ml)
+	return ml
+}
+
+// Receive handles an incoming message.
+func (ml *msgListenerV2) Receive(msg event.MessageMetadata) error {
+	if ml.mailbox != "" && ml.mailbox != msg.Mailbox {
+		// Did not match the watched mailbox name.
+		return nil
+	}
+
+	// Enqueue for websocket.
+	ml.c <- &model.JSONMonitorEventV2{
+		Variant: "message-stored",
+		Header:  metadataToHeader(&msg),
+	}
+
+	return nil
+}
+
+// Delete handles a deleted message.
+func (ml *msgListenerV2) Delete(mailbox string, id string) error {
+	if ml.mailbox != "" && ml.mailbox != mailbox {
+		// Did not match watched mailbox name.
+		return nil
+	}
+
+	// Enqueue for websocket.
+	ml.c <- &model.JSONMonitorEventV2{
+		Variant: "message-deleted",
+		Identifier: &model.JSONMessageIDV2{
+			Mailbox: mailbox,
+			ID:      id,
+		},
+	}
+
+	return nil
+}
+
+// WSReader makes sure the websocket client is still connected, discards any messages from client
+func (ml *msgListenerV2) WSReader(conn *websocket.Conn) {
+	slog := log.With().Str("module", "rest").Str("proto", "WebSocket").
+		Str("remote", conn.RemoteAddr().String()).Logger()
+	defer ml.Close()
+	conn.SetReadLimit(maxMessageSizeV2)
+	conn.SetReadDeadline(time.Now().Add(pongWaitV2))
+	conn.SetPongHandler(func(string) error {
+		slog.Debug().Msg("Got pong")
+		conn.SetReadDeadline(time.Now().Add(pongWaitV2))
+		return nil
+	})
+
+	for {
+		if _, _, err := conn.ReadMessage(); err != nil {
+			if websocket.IsUnexpectedCloseError(
+				err,
+				websocket.CloseNormalClosure,
+				websocket.CloseGoingAway,
+				websocket.CloseNoStatusReceived,
+			) {
+				// Unexpected close code
+				slog.Warn().Err(err).Msg("Socket error")
+			} else {
+				slog.Debug().Msg("Closing socket")
+			}
+			break
+		}
+	}
+}
+
+// WSWriter makes sure the websocket client is still connected
+func (ml *msgListenerV2) WSWriter(conn *websocket.Conn) {
+	ticker := time.NewTicker(pingPeriodV2)
+	defer func() {
+		ticker.Stop()
+		ml.Close()
+	}()
+
+	// Handle messages from hub until msgListener is closed
+	for {
+		select {
+		case event, ok := <-ml.c:
+			conn.SetWriteDeadline(time.Now().Add(writeWaitV2))
+			if !ok {
+				// msgListener closed, exit
+				conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+			if conn.WriteJSON(event) != nil {
+				// Write failed
+				return
+			}
+		case <-ticker.C:
+			// Send ping
+			conn.SetWriteDeadline(time.Now().Add(writeWaitV2))
+			if conn.WriteMessage(websocket.PingMessage, []byte{}) != nil {
+				// Write error
+				return
+			}
+			log.Debug().Str("module", "rest").Str("proto", "WebSocket").
+				Str("remote", conn.RemoteAddr().String()).Msg("Sent ping")
+		}
+	}
+}
+
+// Close removes the listener registration
+func (ml *msgListenerV2) Close() {
+	select {
+	case <-ml.c:
+		// Already closed
+	default:
+		ml.hub.RemoveListener(ml)
+		close(ml.c)
+	}
+}
+
+// MonitorAllMessagesV2 is a web handler which upgrades the connection to a websocket and notifies
+// the client of all messages received.
+func MonitorAllMessagesV2(
+	w http.ResponseWriter, req *http.Request, ctx *web.Context) (err error) {
+	// Upgrade to Websocket.
+	conn, err := upgraderV2.Upgrade(w, req, nil)
+	if err != nil {
+		return err
+	}
+	web.ExpWebSocketConnectsCurrent.Add(1)
+	defer func() {
+		_ = conn.Close()
+		web.ExpWebSocketConnectsCurrent.Add(-1)
+	}()
+	log.Debug().Str("module", "rest").Str("proto", "WebSocket").
+		Str("remote", conn.RemoteAddr().String()).Msg("Upgraded to WebSocket")
+	// Create, register listener; then interact with conn.
+	ml := newMsgListenerV2(ctx.MsgHub, "")
+	go ml.WSWriter(conn)
+	ml.WSReader(conn)
+	return nil
+}
+
+// MonitorMailboxMessagesV2 is a web handler which upgrades the connection to a websocket and
+// notifies the client of messages received by a particular mailbox.
+func MonitorMailboxMessagesV2(
+	w http.ResponseWriter, req *http.Request, ctx *web.Context) (err error) {
+	name, err := ctx.Manager.MailboxForAddress(ctx.Vars["name"])
+	if err != nil {
+		return err
+	}
+	// Upgrade to Websocket.
+	conn, err := upgraderV2.Upgrade(w, req, nil)
+	if err != nil {
+		return err
+	}
+	web.ExpWebSocketConnectsCurrent.Add(1)
+	defer func() {
+		_ = conn.Close()
+		web.ExpWebSocketConnectsCurrent.Add(-1)
+	}()
+	log.Debug().Str("module", "rest").Str("proto", "WebSocket").
+		Str("remote", conn.RemoteAddr().String()).Msg("Upgraded to WebSocket")
+	// Create, register listener; then interact with conn.
+	ml := newMsgListenerV2(ctx.MsgHub, name)
+	go ml.WSWriter(conn)
+	ml.WSReader(conn)
+	return nil
+}

pkg/rest/testutils_test.go

@@ -48,9 +48,8 @@ func setupWebServer(mm message.Manager) *bytes.Buffer {
 			UIDir: "../ui",
 		},
 	}
-	shutdownChan := make(chan bool)
 	SetupRoutes(web.Router.PathPrefix("/api/").Subrouter())
-	web.Initialize(cfg, shutdownChan, mm, &msghub.Hub{})
+	web.NewServer(cfg, mm, &msghub.Hub{})
 
 	return buf
 }

pkg/server/lifecycle.go

@@ -0,0 +1,119 @@
+package server
+
+import (
+	"context"
+	"sync"
+
+	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/luahost"
+	"github.com/inbucket/inbucket/pkg/message"
+	"github.com/inbucket/inbucket/pkg/msghub"
+	"github.com/inbucket/inbucket/pkg/policy"
+	"github.com/inbucket/inbucket/pkg/rest"
+	"github.com/inbucket/inbucket/pkg/server/pop3"
+	"github.com/inbucket/inbucket/pkg/server/smtp"
+	"github.com/inbucket/inbucket/pkg/server/web"
+	"github.com/inbucket/inbucket/pkg/storage"
+	"github.com/inbucket/inbucket/pkg/stringutil"
+	"github.com/inbucket/inbucket/pkg/webui"
+)
+
+// Services holds the configured services.
+type Services struct {
+	MsgHub           *msghub.Hub
+	POP3Server       *pop3.Server
+	RetentionScanner *storage.RetentionScanner
+	SMTPServer       *smtp.Server
+	WebServer        *web.Server
+	ExtHost          *extension.Host
+	LuaHost          *luahost.Host
+	notify           chan error      // Combined notification for failed services.
+	ready            *sync.WaitGroup // Tracks services that have not reported ready.
+}
+
+// FullAssembly wires up a complete Inbucket environment.
+func FullAssembly(conf *config.Root) (*Services, error) {
+	// Configure extensions.
+	extHost := extension.NewHost()
+	luaHost, err := luahost.New(conf.Lua, extHost)
+	if err != nil {
+		return nil, err
+	}
+
+	// Configure storage.
+	store, err := storage.FromConfig(conf.Storage, extHost)
+	if err != nil {
+		return nil, err
+	}
+
+	addrPolicy := &policy.Addressing{Config: conf}
+	// Configure shared components.
+	msgHub := msghub.New(conf.Web.MonitorHistory, extHost)
+	mmanager := &message.StoreManager{AddrPolicy: addrPolicy, Store: store, ExtHost: extHost}
+
+	// Start Retention scanner.
+	retentionScanner := storage.NewRetentionScanner(conf.Storage, store)
+
+	// Configure routes and build HTTP server.
+	prefix := stringutil.MakePathPrefixer(conf.Web.BasePath)
+	webui.SetupRoutes(web.Router.PathPrefix(prefix("/serve/")).Subrouter())
+	rest.SetupRoutes(web.Router.PathPrefix(prefix("/api/")).Subrouter())
+	webServer := web.NewServer(conf, mmanager, msgHub)
+
+	pop3Server := pop3.NewServer(conf.POP3, store)
+	smtpServer := smtp.NewServer(conf.SMTP, mmanager, addrPolicy, extHost)
+
+	return &Services{
+		MsgHub:           msgHub,
+		RetentionScanner: retentionScanner,
+		POP3Server:       pop3Server,
+		SMTPServer:       smtpServer,
+		WebServer:        webServer,
+		ExtHost:          extHost,
+		LuaHost:          luaHost,
+		ready:            &sync.WaitGroup{},
+	}, nil
+}
+
+// Start all services, returns immediately.  Callers may use Notify to detect failed services.
+func (s *Services) Start(ctx context.Context, readyFunc func()) {
+	go s.MsgHub.Start(ctx)
+	go s.WebServer.Start(ctx, s.makeReadyFunc())
+	go s.SMTPServer.Start(ctx, s.makeReadyFunc())
+	go s.POP3Server.Start(ctx, s.makeReadyFunc())
+	go s.RetentionScanner.Start(ctx)
+
+	// Notify when all services report ready.
+	go func() {
+		s.ready.Wait()
+		readyFunc()
+	}()
+}
+
+// Notify merges the error notification channels of all fallible services, allowing the process to
+// be shutdown if needed.
+func (s *Services) Notify() <-chan error {
+	c := make(chan error, 1)
+	go func() {
+		// TODO: What level to log failure.
+		select {
+		case err := <-s.POP3Server.Notify():
+			c <- err
+		case err := <-s.SMTPServer.Notify():
+			c <- err
+		case err := <-s.WebServer.Notify():
+			c <- err
+		}
+	}()
+
+	return c
+}
+
+func (s *Services) makeReadyFunc() func() {
+	s.ready.Add(1)
+	var once sync.Once
+	return func() {
+		once.Do(s.ready.Done)
+	}
+}

pkg/server/pop3/listener.go

@@ -13,47 +13,53 @@ import (
 
 // Server defines an instance of the POP3 server.
 type Server struct {
-	config         config.POP3     // POP3 configuration.
+	config   config.POP3     // POP3 configuration.
-	store          storage.Store   // Mail store.
+	store    storage.Store   // Mail store.
-	listener       net.Listener    // TCP listener.
+	listener net.Listener    // TCP listener.
-	globalShutdown chan bool       // Inbucket shutdown signal.
+	wg       *sync.WaitGroup // Waitgroup tracking sessions.
-	wg             *sync.WaitGroup // Waitgroup tracking sessions.
+	notify   chan error      // Notify on fatal error.
 }
 
-// New creates a new Server struct.
+// NewServer creates a new, unstarted, POP3 server.
-func New(pop3Config config.POP3, shutdownChan chan bool, store storage.Store) *Server {
+func NewServer(pop3Config config.POP3, store storage.Store) *Server {
 	return &Server{
-		config:         pop3Config,
+		config: pop3Config,
-		store:          store,
+		store:  store,
-		globalShutdown: shutdownChan,
+		wg:     new(sync.WaitGroup),
-		wg:             new(sync.WaitGroup),
+		notify: make(chan error, 1),
 	}
 }
 
 // Start the server and listen for connections
-func (s *Server) Start(ctx context.Context) {
+func (s *Server) Start(ctx context.Context, readyFunc func()) {
 	slog := log.With().Str("module", "pop3").Str("phase", "startup").Logger()
 	addr, err := net.ResolveTCPAddr("tcp4", s.config.Addr)
 	if err != nil {
 		slog.Error().Err(err).Msg("Failed to build tcp4 address")
-		s.emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
 	slog.Info().Str("addr", addr.String()).Msg("POP3 listening on tcp4")
 	s.listener, err = net.ListenTCP("tcp4", addr)
 	if err != nil {
 		slog.Error().Err(err).Msg("Failed to start tcp4 listener")
-		s.emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
-	// Listener go routine.
+
+	// Start listener go routine.
 	go s.serve(ctx)
+	readyFunc()
+
 	// Wait for shutdown.
 	select {
 	case _ = <-ctx.Done():
 	}
 	slog = log.With().Str("module", "pop3").Str("phase", "shutdown").Logger()
 	slog.Debug().Msg("POP3 shutdown requested, connections will be drained")
+
 	// Closing the listener will cause the serve() go routine to exit.
 	if err := s.listener.Close(); err != nil {
 		slog.Error().Err(err).Msg("Failed to close POP3 listener")
@@ -88,7 +94,8 @@ func (s *Server) serve(ctx context.Context) {
 					return
 				default:
 					// Something went wrong.
-					s.emergencyShutdown()
+					s.notify <- err
+					close(s.notify)
 					return
 				}
 			}
@@ -100,18 +107,14 @@ func (s *Server) serve(ctx context.Context) {
 	}
 }
 
-func (s *Server) emergencyShutdown() {
-	// Shutdown Inbucket
-	select {
-	case _ = <-s.globalShutdown:
-	default:
-		close(s.globalShutdown)
-	}
-}
-
 // Drain causes the caller to block until all active POP3 sessions have finished
 func (s *Server) Drain() {
 	// Wait for sessions to close
 	s.wg.Wait()
 	log.Debug().Str("module", "pop3").Str("phase", "shutdown").Msg("POP3 connections have drained")
 }
+
+// Notify allows the running POP3 server to be monitored for a fatal error.
+func (s *Server) Notify() <-chan error {
+	return s.notify
+}

pkg/server/smtp/handler.go

@@ -13,9 +13,9 @@ import (
 	"strings"
 	"time"
 
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/policy"
 	"github.com/rs/zerolog"
-	"github.com/rs/zerolog/log"
 )
 
 // State tracks the current mode of our SMTP state machine.
@@ -54,11 +54,11 @@ const (
 	QUIT
 )
 
-// fromRegex captures the from address and optional BODY=8BITMIME clause.  Matches FROM, while
+// fromRegex captures the from address and optional parameters.  Matches FROM, while accepting '>'
-// accepting '>' as quoted pair and in double quoted strings (?i) makes the regex case insensitive,
+// as quoted pair and in double quoted strings (?i) makes the regex case insensitive, (?:) is
-// (?:) is non-grouping sub-match
+// non-grouping sub-match.  Accepts empty angle bracket value in options for 'AUTH=<>'.
 var fromRegex = regexp.MustCompile(
-	"(?i)^FROM:\\s*<((?:(?:\\\\>|[^>])+|\"[^\"]+\"@[^>])+)?>( [\\w= ]+)?$")
+	`(?i)^FROM:\s*<((?:(?:\\>|[^>])+|"[^"]+"@[^>])+)?>( ([\w= ]|=<>)+)?$`)
 
 func (s State) String() string {
 	switch s {
@@ -144,8 +144,8 @@ func (s *Session) String() string {
  *  4. If bad cmd, respond error
  *  5. Goto 2
  */
-func (s *Server) startSession(id int, conn net.Conn) {
+func (s *Server) startSession(id int, conn net.Conn, logger zerolog.Logger) {
-	logger := log.Hook(logHook{}).With().
+	logger = logger.Hook(logHook{}).With().
 		Str("module", "smtp").
 		Str("remote", conn.RemoteAddr().String()).
 		Int("session", id).Logger()
@@ -384,7 +384,8 @@ func (s *Session) readyHandler(cmd string, arg string) {
 			return
 		}
 		from := m[1]
-		if _, _, err := policy.ParseEmailAddress(from); from != "" && err != nil {
+		localpart, domain, err := policy.ParseEmailAddress(from)
+		if from != "" && err != nil {
 			s.send("501 Bad sender address syntax")
 			s.logger.Warn().Msgf("Bad address as MAIL arg: %q, %s", from, err)
 			return
@@ -416,10 +417,22 @@ func (s *Session) readyHandler(cmd string, arg string) {
 				}
 			}
 		}
-		s.from = from
+
-		s.logger.Info().Msgf("Mail from: %v", from)
+		// Process through extensions.
-		s.send(fmt.Sprintf("250 Roger, accepting mail from <%v>", from))
+		extResult := s.extHost.Events.BeforeMailAccepted.Emit(
-		s.enterState(MAIL)
+			&event.AddressParts{Local: localpart, Domain: domain})
+
+		if extResult == nil || *extResult {
+			// Permitted by extension, or none had an opinion.
+			s.from = from
+			s.logger.Info().Msgf("Mail from: %v", from)
+			s.send(fmt.Sprintf("250 Roger, accepting mail from <%v>", from))
+			s.enterState(MAIL)
+		} else {
+			s.send("550 Mail denied by policy")
+			s.logger.Warn().Msgf("Extension denied mail from <%v>", from)
+			return
+		}
 	} else if cmd == "EHLO" {
 		// Reset session
 		s.logger.Debug().Msgf("Resetting session state on EHLO request")
@@ -615,11 +628,13 @@ func (s *Session) parseCmd(line string) (cmd string, arg string, ok bool) {
 // parseArgs takes the arguments proceeding a command and files them
 // into a map[string]string after uppercasing each key.  Sample arg
 // string:
-//		" BODY=8BITMIME SIZE=1024"
+//
+//	" BODY=8BITMIME SIZE=1024"
+//
 // The leading space is mandatory.
 func (s *Session) parseArgs(arg string) (args map[string]string, ok bool) {
 	args = make(map[string]string)
-	re := regexp.MustCompile(` (\w+)=(\w+)`)
+	re := regexp.MustCompile(` (\w+)=(\w+|<>)`)
 	pm := re.FindAllStringSubmatch(arg, -1)
 	if pm == nil {
 		s.logger.Warn().Msgf("Failed to parse arg string: %q", arg)

pkg/server/smtp/handler_test.go

@@ -1,22 +1,23 @@
 package smtp
 
 import (
-	"bytes"
 	"fmt"
 	"io"
 
-	"log"
 	"net"
 	"net/textproto"
-	"os"
 	"testing"
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/policy"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/test"
+	"github.com/rs/zerolog"
+	"github.com/stretchr/testify/assert"
 )
 
 type scriptStep struct {
@@ -24,14 +25,44 @@ type scriptStep struct {
 	expect int
 }
 
-// Test commands in GREET state
+// Test valid commands in GREET state.
+func TestGreetStateValidCommands(t *testing.T) {
+	ds := test.NewStore()
+	server := setupSMTPServer(ds, extension.NewHost())
+
+	tests := []scriptStep{
+		{"HELO mydomain", 250},
+		{"HELO mydom.com", 250},
+		{"HelO mydom.com", 250},
+		{"helo 127.0.0.1", 250},
+		{"HELO ABC", 250},
+		{"EHLO mydomain", 250},
+		{"EHLO mydom.com", 250},
+		{"EhlO mydom.com", 250},
+		{"ehlo 127.0.0.1", 250},
+		{"EHLO a", 250},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.send, func(t *testing.T) {
+			defer server.Drain() // Required to prevent test logging data race.
+			script := []scriptStep{
+				tc,
+				{"QUIT", 221}}
+			if err := playSession(t, server, script); err != nil {
+				t.Error(err)
+			}
+		})
+	}
+}
+
+// Test invalid commands in GREET state.
 func TestGreetState(t *testing.T) {
 	ds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(ds)
+	server := setupSMTPServer(ds, extension.NewHost())
-	defer teardown()
+	defer server.Drain() // Required to prevent test logging data race.
 
-	// Test out some mangled HELOs
+	tests := []scriptStep{
-	script := []scriptStep{
 		{"HELO", 501},
 		{"EHLO", 501},
 		{"HELLO", 500},
@@ -39,57 +70,24 @@ func TestGreetState(t *testing.T) {
 		{"hello", 500},
 		{"Outlook", 500},
 	}
-	if err := playSession(t, server, script); err != nil {
-		t.Error(err)
-	}
 
-	// Valid HELOs
+	for _, tc := range tests {
-	if err := playSession(t, server, []scriptStep{{"HELO mydomain", 250}}); err != nil {
+		t.Run(tc.send, func(t *testing.T) {
-		t.Error(err)
+			defer server.Drain() // Required to prevent test logging data race.
-	}
+			script := []scriptStep{
-	if err := playSession(t, server, []scriptStep{{"HELO mydom.com", 250}}); err != nil {
+				tc,
-		t.Error(err)
+				{"QUIT", 221}}
-	}
+			if err := playSession(t, server, script); err != nil {
-	if err := playSession(t, server, []scriptStep{{"HelO mydom.com", 250}}); err != nil {
+				t.Error(err)
-		t.Error(err)
+			}
-	}
+		})
-	if err := playSession(t, server, []scriptStep{{"helo 127.0.0.1", 250}}); err != nil {
-		t.Error(err)
-	}
-	if err := playSession(t, server, []scriptStep{{"HELO ABC", 250}}); err != nil {
-		t.Error(err)
-	}
-
-	// Valid EHLOs
-	if err := playSession(t, server, []scriptStep{{"EHLO mydomain", 250}}); err != nil {
-		t.Error(err)
-	}
-	if err := playSession(t, server, []scriptStep{{"EHLO mydom.com", 250}}); err != nil {
-		t.Error(err)
-	}
-	if err := playSession(t, server, []scriptStep{{"EhlO mydom.com", 250}}); err != nil {
-		t.Error(err)
-	}
-	if err := playSession(t, server, []scriptStep{{"ehlo 127.0.0.1", 250}}); err != nil {
-		t.Error(err)
-	}
-	if err := playSession(t, server, []scriptStep{{"EHLO a", 250}}); err != nil {
-		t.Error(err)
-	}
-
-	if t.Failed() {
-		// Wait for handler to finish logging
-		time.Sleep(2 * time.Second)
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
 	}
 }
 
-// Test commands in READY state
 func TestEmptyEnvelope(t *testing.T) {
 	ds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(ds)
+	server := setupSMTPServer(ds, extension.NewHost())
-	defer teardown()
+	defer server.Drain()
 
 	// Test out some empty envelope without blanks
 	script := []scriptStep{
@@ -97,8 +95,6 @@ func TestEmptyEnvelope(t *testing.T) {
 		{"MAIL FROM:<>", 250},
 	}
 	if err := playSession(t, server, script); err != nil {
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
 		t.Error(err)
 	}
 
@@ -108,17 +104,15 @@ func TestEmptyEnvelope(t *testing.T) {
 		{"MAIL FROM: <>", 250},
 	}
 	if err := playSession(t, server, script); err != nil {
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
 		t.Error(err)
 	}
 }
 
-// Test AUTH
+// Test AUTH commands.
 func TestAuth(t *testing.T) {
 	ds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(ds)
+	server := setupSMTPServer(ds, extension.NewHost())
-	defer teardown()
+	defer server.Drain()
 
 	// PLAIN AUTH
 	script := []scriptStep{
@@ -149,24 +143,67 @@ func TestAuth(t *testing.T) {
 	if err := playSession(t, server, script); err != nil {
 		t.Error(err)
 	}
+}
 
-	if t.Failed() {
+// Test TLS commands.
-		// Wait for handler to finish logging
+func TestTLS(t *testing.T) {
-		time.Sleep(2 * time.Second)
+	ds := test.NewStore()
-		// Dump buffered log data if there was a failure
+	server := setupSMTPServer(ds, extension.NewHost())
-		_, _ = io.Copy(os.Stderr, logbuf)
+	defer server.Drain()
+
+	// Test Start TLS parsing.
+	script := []scriptStep{
+		{"HELO localhost", 250},
+		{"STARTTLS", 454}, // TLS unconfigured.
+	}
+
+	if err := playSession(t, server, script); err != nil {
+		t.Error(err)
 	}
 }
 
-// Test commands in READY state
+// Test valid commands in READY state.
-func TestReadyState(t *testing.T) {
+func TestReadyStateValidCommands(t *testing.T) {
 	ds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(ds)
+	server := setupSMTPServer(ds, extension.NewHost())
-	defer teardown()
 
-	// Test out some mangled READY commands
+	// Test out some valid MAIL commands
-	script := []scriptStep{
+	tests := []scriptStep{
-		{"HELO localhost", 250},
+		{"MAIL FROM:<john@gmail.com>", 250},
+		{"MAIL FROM: <john@gmail.com>", 250},
+		{"MAIL FROM: <john@gmail.com> BODY=8BITMIME", 250},
+		{"MAIL FROM:<john@gmail.com> SIZE=1024", 250},
+		{"MAIL FROM:<john@gmail.com> SIZE=1024 BODY=8BITMIME", 250},
+		{"MAIL FROM:<bounces@onmicrosoft.com> SIZE=4096 AUTH=<>", 250},
+		{"MAIL FROM:<b@o.com> SIZE=4096 AUTH=<> BODY=7BIT", 250},
+		{"MAIL FROM:<host!host!user/data@foo.com>", 250},
+		{"MAIL FROM:<\"first last\"@space.com>", 250},
+		{"MAIL FROM:<user\\@internal@external.com>", 250},
+		{"MAIL FROM:<user\\>name@host.com>", 250},
+		{"MAIL FROM:<\"user>name\"@host.com>", 250},
+		{"MAIL FROM:<\"user@internal\"@external.com>", 250},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.send, func(t *testing.T) {
+			defer server.Drain()
+			script := []scriptStep{
+				{"HELO localhost", 250},
+				tc,
+				{"QUIT", 221}}
+			if err := playSession(t, server, script); err != nil {
+				t.Error(err)
+			}
+		})
+	}
+}
+
+// Test invalid commands in READY state.
+func TestReadyStateInvalidCommands(t *testing.T) {
+	ds := test.NewStore()
+	server := setupSMTPServer(ds, extension.NewHost())
+
+	tests := []scriptStep{
 		{"FOOB", 500},
 		{"HELO", 503},
 		{"DATA", 503},
@@ -178,59 +215,27 @@ func TestReadyState(t *testing.T) {
 		{"MAIL FROM:<first@last@gmail.com>", 501},
 		{"MAIL FROM:<first last@gmail.com>", 501},
 	}
-	if err := playSession(t, server, script); err != nil {
+
-		t.Error(err)
+	for _, tc := range tests {
+		t.Run(tc.send, func(t *testing.T) {
+			defer server.Drain()
+			script := []scriptStep{
+				{"HELO localhost", 250},
+				tc,
+				{"QUIT", 221}}
+			if err := playSession(t, server, script); err != nil {
+				t.Error(err)
+			}
+		})
 	}
 
-	// Test out some valid MAIL commands
-	script = []scriptStep{
-		{"HELO localhost", 250},
-		{"MAIL FROM:<john@gmail.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM: <john@gmail.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM: <john@gmail.com> BODY=8BITMIME", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<john@gmail.com> SIZE=1024", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<host!host!user/data@foo.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<\"first last\"@space.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<user\\@internal@external.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<user\\>name@host.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<\"user>name\"@host.com>", 250},
-		{"RSET", 250},
-		{"MAIL FROM:<\"user@internal\"@external.com>", 250},
-	}
-	if err := playSession(t, server, script); err != nil {
-		t.Error(err)
-	}
-
-	// Test Start TLS parsing.
-	script = []scriptStep{
-		{"HELO localhost", 250},
-		{"STARTTLS", 454}, // TLS unconfigured.
-	}
-	if err := playSession(t, server, script); err != nil {
-		t.Error(err)
-	}
-
-	if t.Failed() {
-		// Wait for handler to finish logging
-		time.Sleep(2 * time.Second)
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
-	}
 }
 
 // Test commands in MAIL state
 func TestMailState(t *testing.T) {
 	mds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(mds)
+	server := setupSMTPServer(mds, extension.NewHost())
-	defer teardown()
+	defer server.Drain()
 
 	// Test out some mangled READY commands
 	script := []scriptStep{
@@ -262,6 +267,8 @@ func TestMailState(t *testing.T) {
 		{"RSET", 250},
 		{"MAIL FROM:<john@gmail.com>", 250},
 		{`RCPT TO:<"first/last"@host.com`, 250},
+		{"RCPT TO:<u1@[127.0.0.1]>", 250},
+		{"RCPT TO:<u1@[IPv6:2001:db8:aaaa:1::100]>", 250},
 	}
 	if err := playSession(t, server, script); err != nil {
 		t.Error(err)
@@ -329,23 +336,16 @@ func TestMailState(t *testing.T) {
 	if err := playSession(t, server, script); err != nil {
 		t.Error(err)
 	}
-
-	if t.Failed() {
-		// Wait for handler to finish logging
-		time.Sleep(2 * time.Second)
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
-	}
 }
 
 // Test commands in DATA state
 func TestDataState(t *testing.T) {
 	mds := test.NewStore()
-	server, logbuf, teardown := setupSMTPServer(mds)
+	server := setupSMTPServer(mds, extension.NewHost())
-	defer teardown()
+	defer server.Drain()
 
 	var script []scriptStep
-	pipe := setupSMTPSession(server)
+	pipe := setupSMTPSession(t, server)
 	c := textproto.NewConn(pipe)
 
 	if code, _, err := c.ReadCodeLine(220); err != nil {
@@ -360,6 +360,7 @@ func TestDataState(t *testing.T) {
 	if err := playScriptAgainst(t, c, script); err != nil {
 		t.Error(err)
 	}
+
 	// Send a message
 	body := `To: u1@gmail.com
 From: john@gmail.com
@@ -373,9 +374,11 @@ Hi!
 	if code, _, err := c.ReadCodeLine(250); err != nil {
 		t.Errorf("Expected a 250 greeting, got %v", code)
 	}
+	_, _ = c.Cmd("QUIT")
+	_, _, _ = c.ReadCodeLine(221)
 
 	// Test with no useful headers.
-	pipe = setupSMTPSession(server)
+	pipe = setupSMTPSession(t, server)
 	c = textproto.NewConn(pipe)
 	if code, _, err := c.ReadCodeLine(220); err != nil {
 		t.Errorf("Expected a 220 greeting, got %v", code)
@@ -389,29 +392,25 @@ Hi!
 	if err := playScriptAgainst(t, c, script); err != nil {
 		t.Error(err)
 	}
+
 	// Send a message
 	body = `X-Useless-Header: true
 
-Hi! Can you still deliver this?
+	Hi! Can you still deliver this?
-`
+	`
 	dw = c.DotWriter()
 	_, _ = io.WriteString(dw, body)
 	_ = dw.Close()
 	if code, _, err := c.ReadCodeLine(250); err != nil {
 		t.Errorf("Expected a 250 greeting, got %v", code)
 	}
-
+	_, _ = c.Cmd("QUIT")
-	if t.Failed() {
+	_, _, _ = c.ReadCodeLine(221)
-		// Wait for handler to finish logging
-		time.Sleep(2 * time.Second)
-		// Dump buffered log data if there was a failure
-		_, _ = io.Copy(os.Stderr, logbuf)
-	}
 }
 
 // playSession creates a new session, reads the greeting and then plays the script
 func playSession(t *testing.T, server *Server, script []scriptStep) error {
-	pipe := setupSMTPSession(server)
+	pipe := setupSMTPSession(t, server)
 	c := textproto.NewConn(pipe)
 
 	if code, _, err := c.ReadCodeLine(220); err != nil {
@@ -452,6 +451,93 @@ func playScriptAgainst(t *testing.T, c *textproto.Conn, script []scriptStep) err
 	return nil
 }
 
+// Tests "MAIL FROM" emits BeforeMailAccepted event.
+func TestBeforeMailAcceptedEventEmitted(t *testing.T) {
+	ds := test.NewStore()
+	extHost := extension.NewHost()
+	server := setupSMTPServer(ds, extHost)
+	defer server.Drain()
+
+	var got *event.AddressParts
+	extHost.Events.BeforeMailAccepted.AddListener(
+		"test",
+		func(addr event.AddressParts) *bool {
+			got = &addr
+			return nil
+		})
+
+	// Play and verify SMTP session.
+	script := []scriptStep{
+		{"HELO localhost", 250},
+		{"MAIL FROM:<john@gmail.com>", 250},
+		{"QUIT", 221}}
+	if err := playSession(t, server, script); err != nil {
+		t.Error(err)
+	}
+
+	assert.NotNil(t, got, "BeforeMailListener did not receive Address")
+	assert.Equal(t, "john", got.Local, "Address local part had wrong value")
+	assert.Equal(t, "gmail.com", got.Domain, "Address domain part had wrong value")
+}
+
+// Test "MAIL FROM" acts on BeforeMailAccepted event result.
+func TestBeforeMailAcceptedEventResponse(t *testing.T) {
+	ds := test.NewStore()
+	extHost := extension.NewHost()
+	server := setupSMTPServer(ds, extHost)
+	defer server.Drain()
+
+	var shouldReturn *bool
+	var gotEvent *event.AddressParts
+	extHost.Events.BeforeMailAccepted.AddListener(
+		"test",
+		func(addr event.AddressParts) *bool {
+			gotEvent = &addr
+			return shouldReturn
+		})
+
+	allowRes := true
+	denyRes := false
+	tcs := map[string]struct {
+		script   scriptStep // Command to send and SMTP code expected.
+		eventRes *bool      // Response to send from event listener.
+	}{
+		"allow": {
+			script:   scriptStep{"MAIL FROM:<john@gmail.com>", 250},
+			eventRes: &allowRes,
+		},
+		"deny": {
+			script:   scriptStep{"MAIL FROM:<john@gmail.com>", 550},
+			eventRes: &denyRes,
+		},
+		"defer": {
+			script:   scriptStep{"MAIL FROM:<john@gmail.com>", 250},
+			eventRes: nil,
+		},
+	}
+
+	for name, tc := range tcs {
+		tc := tc
+		t.Run(name, func(t *testing.T) {
+			// Reset event listener.
+			shouldReturn = tc.eventRes
+			gotEvent = nil
+
+			// Play and verify SMTP session.
+			script := []scriptStep{
+				{"HELO localhost", 250},
+				tc.script,
+				{"QUIT", 221}}
+			if err := playSession(t, server, script); err != nil {
+				t.Error(err)
+			}
+
+			assert.NotNil(t, gotEvent, "BeforeMailListener did not receive Address")
+		})
+	}
+
+}
+
 // net.Pipe does not implement deadlines
 type mockConn struct {
 	net.Conn
@@ -461,7 +547,7 @@ func (m *mockConn) SetDeadline(t time.Time) error      { return nil }
 func (m *mockConn) SetReadDeadline(t time.Time) error  { return nil }
 func (m *mockConn) SetWriteDeadline(t time.Time) error { return nil }
 
-func setupSMTPServer(ds storage.Store) (s *Server, buf *bytes.Buffer, teardown func()) {
+func setupSMTPServer(ds storage.Store, extHost *extension.Host) *Server {
 	cfg := &config.Root{
 		MailboxNaming: config.FullNaming,
 		SMTP: config.SMTP{
@@ -474,28 +560,24 @@ func setupSMTPServer(ds storage.Store) (s *Server, buf *bytes.Buffer, teardown f
 			Timeout:         5,
 		},
 	}
-	// Capture log output.
+
-	buf = new(bytes.Buffer)
-	log.SetOutput(buf)
 	// Create a server, don't start it.
-	shutdownChan := make(chan bool)
-	teardown = func() {
-		close(shutdownChan)
-	}
 	addrPolicy := &policy.Addressing{Config: cfg}
 	manager := &message.StoreManager{Store: ds}
-	s = NewServer(cfg.SMTP, shutdownChan, manager, addrPolicy)
+
-	return s, buf, teardown
+	return NewServer(cfg.SMTP, manager, addrPolicy, extHost)
 }
 
 var sessionNum int
 
-func setupSMTPSession(server *Server) net.Conn {
+func setupSMTPSession(t *testing.T, server *Server) net.Conn {
-	// Pair of pipes to communicate.
+	logger := zerolog.New(zerolog.NewTestWriter(t))
 	serverConn, clientConn := net.Pipe()
+
 	// Start the session.
 	server.wg.Add(1)
 	sessionNum++
-	go server.startSession(sessionNum, &mockConn{serverConn})
+	go server.startSession(sessionNum, &mockConn{serverConn}, logger)
+
 	return clientConn
 }

pkg/server/smtp/listener.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/metric"
 	"github.com/inbucket/inbucket/pkg/policy"
@@ -58,21 +59,22 @@ func init() {
 
 // Server holds the configuration and state of our SMTP server.
 type Server struct {
-	config         config.SMTP        // SMTP configuration.
+	config     config.SMTP        // SMTP configuration.
-	addrPolicy     *policy.Addressing // Address policy.
+	tlsConfig  *tls.Config        // TLS encryption configuration.
-	globalShutdown chan bool          // Shuts down Inbucket.
+	addrPolicy *policy.Addressing // Address policy.
-	manager        message.Manager    // Used to deliver messages.
+	manager    message.Manager    // Used to deliver messages.
-	listener       net.Listener       // Incoming network connections.
+	extHost    *extension.Host    // Extension event processor.
-	wg             *sync.WaitGroup    // Waitgroup tracks individual sessions.
+	listener   net.Listener       // Incoming network connections.
-	tlsConfig      *tls.Config
+	wg         *sync.WaitGroup    // Waitgroup tracks individual sessions.
+	notify     chan error         // Notify on fatal error.
 }
 
-// NewServer creates a new Server instance with the specificed config.
+// NewServer creates a new, unstarted, SMTP server instance with the specificed config.
 func NewServer(
 	smtpConfig config.SMTP,
-	globalShutdown chan bool,
 	manager message.Manager,
 	apolicy *policy.Addressing,
+	extHost *extension.Host,
 ) *Server {
 	slog := log.With().Str("module", "smtp").Str("phase", "tls").Logger()
 	tlsConfig := &tls.Config{}
@@ -90,37 +92,44 @@ func NewServer(
 	}
 
 	return &Server{
-		config:         smtpConfig,
+		config:     smtpConfig,
-		globalShutdown: globalShutdown,
+		tlsConfig:  tlsConfig,
-		manager:        manager,
+		manager:    manager,
-		addrPolicy:     apolicy,
+		addrPolicy: apolicy,
-		wg:             new(sync.WaitGroup),
+		extHost:    extHost,
-		tlsConfig:      tlsConfig,
+		wg:         new(sync.WaitGroup),
+		notify:     make(chan error, 1),
 	}
 }
 
 // Start the listener and handle incoming connections.
-func (s *Server) Start(ctx context.Context) {
+func (s *Server) Start(ctx context.Context, readyFunc func()) {
 	slog := log.With().Str("module", "smtp").Str("phase", "startup").Logger()
 	addr, err := net.ResolveTCPAddr("tcp4", s.config.Addr)
 	if err != nil {
 		slog.Error().Err(err).Msg("Failed to build tcp4 address")
-		s.emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
 	slog.Info().Str("addr", addr.String()).Msg("SMTP listening on tcp4")
 	s.listener, err = net.ListenTCP("tcp4", addr)
 	if err != nil {
 		slog.Error().Err(err).Msg("Failed to start tcp4 listener")
-		s.emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
-	// Listener go routine.
+
+	// Start listener go routine.
 	go s.serve(ctx)
+	readyFunc()
+
 	// Wait for shutdown.
 	<-ctx.Done()
 	slog = log.With().Str("module", "smtp").Str("phase", "shutdown").Logger()
 	slog.Debug().Msg("SMTP shutdown requested, connections will be drained")
+
 	// Closing the listener will cause the serve() go routine to exit.
 	if err := s.listener.Close(); err != nil {
 		slog.Error().Err(err).Msg("Failed to close SMTP listener")
@@ -156,7 +165,8 @@ func (s *Server) serve(ctx context.Context) {
 					return
 				default:
 					// Something went wrong.
-					s.emergencyShutdown()
+					s.notify <- err
+					close(s.notify)
 					return
 				}
 			}
@@ -164,23 +174,18 @@ func (s *Server) serve(ctx context.Context) {
 			tempDelay = 0
 			expConnectsTotal.Add(1)
 			s.wg.Add(1)
-			go s.startSession(sessionID, conn)
+			go s.startSession(sessionID, conn, log.Logger)
 		}
 	}
 }
 
-func (s *Server) emergencyShutdown() {
-	// Shutdown Inbucket.
-	select {
-	case <-s.globalShutdown:
-	default:
-		close(s.globalShutdown)
-	}
-}
-
 // Drain causes the caller to block until all active SMTP sessions have finished
 func (s *Server) Drain() {
 	// Wait for sessions to close.
 	s.wg.Wait()
-	log.Debug().Str("module", "smtp").Str("phase", "shutdown").Msg("SMTP connections have drained")
+}
+
+// Notify allows the running SMTP server to be monitored for a fatal error.
+func (s *Server) Notify() <-chan error {
+	return s.notify
 }

pkg/server/web/server.go

@@ -31,10 +31,9 @@ var (
 	// incoming requests to the correct handler function
 	Router = mux.NewRouter()
 
-	rootConfig     *config.Root
+	rootConfig *config.Root
-	server         *http.Server
+	server     *http.Server
-	listener       net.Listener
+	listener   net.Listener
-	globalShutdown chan bool
 
 	// ExpWebSocketConnectsCurrent tracks the number of open WebSockets
 	ExpWebSocketConnectsCurrent = new(expvar.Int)
@@ -45,15 +44,19 @@ func init() {
 	m.Set("WebSocketConnectsCurrent", ExpWebSocketConnectsCurrent)
 }
 
-// Initialize sets up things for unit tests or the Start() method.
+// Server defines an instance of the Web server.
-func Initialize(
+type Server struct {
+	// TODO Migrate global vars here.
+	notify chan error // Notify on fatal error.
+}
+
+// NewServer sets up things for unit tests or the Start() method.
+func NewServer(
 	conf *config.Root,
-	shutdownChan chan bool,
 	mm message.Manager,
-	mh *msghub.Hub) {
+	mh *msghub.Hub) *Server {
 
 	rootConfig = conf
-	globalShutdown = shutdownChan
 
 	// NewContext() will use this DataStore for the web handlers.
 	msgHub = mh
@@ -118,10 +121,16 @@ func Initialize(
 		http.StatusNotFound, "No route matches URI path")
 	Router.MethodNotAllowedHandler = noMatchHandler(
 		http.StatusMethodNotAllowed, "Method not allowed for URI path")
+
+	s := &Server{
+		notify: make(chan error, 1),
+	}
+
+	return s
 }
 
 // Start begins listening for HTTP requests
-func Start(ctx context.Context) {
+func (s *Server) Start(ctx context.Context, readyFunc func()) {
 	server = &http.Server{
 		Addr:         rootConfig.Web.Addr,
 		Handler:      requestLoggingWrapper(Router),
@@ -137,12 +146,14 @@ func Start(ctx context.Context) {
 	if err != nil {
 		log.Error().Str("module", "web").Str("phase", "startup").Err(err).
 			Msg("HTTP failed to start TCP4 listener")
-		emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
 
-	// Listener go routine
+	// Start listener go routine
-	go serve(ctx)
+	go s.serve(ctx)
+	readyFunc()
 
 	// Wait for shutdown
 	select {
@@ -176,7 +187,7 @@ func appConfigCookie(webConfig config.Web) *http.Cookie {
 }
 
 // serve begins serving HTTP requests
-func serve(ctx context.Context) {
+func (s *Server) serve(ctx context.Context) {
 	// server.Serve blocks until we close the listener
 	err := server.Serve(listener)
 
@@ -186,16 +197,13 @@ func serve(ctx context.Context) {
 	default:
 		log.Error().Str("module", "web").Str("phase", "startup").Err(err).
 			Msg("HTTP server failed")
-		emergencyShutdown()
+		s.notify <- err
+		close(s.notify)
 		return
 	}
 }
 
-func emergencyShutdown() {
+// Notify allows the running Web server to be monitored for a fatal error.
-	// Shutdown Inbucket
+func (s *Server) Notify() <-chan error {
-	select {
+	return s.notify
-	case _ = <-globalShutdown:
-	default:
-		close(globalShutdown)
-	}
 }

pkg/storage/file/fstore.go

@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/stringutil"
 	"github.com/rs/zerolog/log"
@@ -45,10 +47,11 @@ type Store struct {
 	mailPath      string
 	messageCap    int
 	bufReaderPool sync.Pool
+	extHost       *extension.Host
 }
 
 // New creates a new DataStore object using the specified path
-func New(cfg config.Storage) (storage.Store, error) {
+func New(cfg config.Storage, extHost *extension.Host) (storage.Store, error) {
 	path := cfg.Params["path"]
 	if path == "" {
 		return nil, fmt.Errorf("'path' parameter not specified")
@@ -70,6 +73,7 @@ func New(cfg config.Storage) (storage.Store, error) {
 				return bufio.NewReader(nil)
 			},
 		},
+		extHost: extHost,
 	}, nil
 }
 
@@ -183,6 +187,17 @@ func (fs *Store) PurgeMessages(mailbox string) error {
 	mb := fs.mbox(mailbox)
 	mb.Lock()
 	defer mb.Unlock()
+
+	// Emit delete events.
+	if !mb.indexLoaded {
+		if err := mb.readIndex(); err != nil {
+			return err
+		}
+	}
+	for _, m := range mb.messages {
+		fs.extHost.Events.AfterMessageDeleted.Emit(message.MakeMetadata(m))
+	}
+
 	return mb.purge()
 }
 

pkg/storage/file/fstore_test.go

@@ -14,6 +14,8 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/test"
@@ -22,18 +24,19 @@ import (
 
 // TestSuite runs storage package test suite on file store.
 func TestSuite(t *testing.T) {
-	test.StoreSuite(t, func(conf config.Storage) (storage.Store, func(), error) {
+	test.StoreSuite(t,
-		ds, _ := setupDataStore(conf)
+		func(conf config.Storage, extHost *extension.Host) (storage.Store, func(), error) {
-		destroy := func() {
+			ds, _ := setupDataStore(conf, extHost)
-			teardownDataStore(ds)
+			destroy := func() {
-		}
+				teardownDataStore(ds)
-		return ds, destroy, nil
+			}
-	})
+			return ds, destroy, nil
+		})
 }
 
 // Test directory structure created by filestore
 func TestFSDirStructure(t *testing.T) {
-	ds, logbuf := setupDataStore(config.Storage{})
+	ds, logbuf := setupDataStore(config.Storage{}, extension.NewHost())
 	defer teardownDataStore(ds)
 	root := ds.path
 
@@ -111,7 +114,7 @@ func TestFSDirStructure(t *testing.T) {
 
 // Test missing files
 func TestFSMissing(t *testing.T) {
-	ds, logbuf := setupDataStore(config.Storage{})
+	ds, logbuf := setupDataStore(config.Storage{}, extension.NewHost())
 	defer teardownDataStore(ds)
 
 	mbName := "fred"
@@ -146,7 +149,7 @@ func TestFSMissing(t *testing.T) {
 
 // Test Get the latest message
 func TestGetLatestMessage(t *testing.T) {
-	ds, logbuf := setupDataStore(config.Storage{})
+	ds, logbuf := setupDataStore(config.Storage{}, extension.NewHost())
 	defer teardownDataStore(ds)
 
 	// james hashes to 474ba67bdb289c6263b36dfd8a7bed6c85b04943
@@ -188,22 +191,25 @@ func TestGetLatestMessage(t *testing.T) {
 }
 
 // setupDataStore creates a new FileDataStore in a temporary directory
-func setupDataStore(cfg config.Storage) (*Store, *bytes.Buffer) {
+func setupDataStore(cfg config.Storage, extHost *extension.Host) (*Store, *bytes.Buffer) {
 	path, err := ioutil.TempDir("", "inbucket")
 	if err != nil {
 		panic(err)
 	}
+
 	// Capture log output.
 	buf := new(bytes.Buffer)
 	log.SetOutput(buf)
+
 	if cfg.Params == nil {
 		cfg.Params = make(map[string]string)
 	}
 	cfg.Params["path"] = path
-	s, err := New(cfg)
+	s, err := New(cfg, extHost)
 	if err != nil {
 		panic(err)
 	}
+
 	return s.(*Store), buf
 }
 
@@ -211,7 +217,7 @@ func setupDataStore(cfg config.Storage) (*Store, *bytes.Buffer) {
 // the size of the generated message.
 func deliverMessage(ds *Store, mbName string, subject string, date time.Time) (string, int64) {
 	// Build message for delivery
-	meta := message.Metadata{
+	meta := event.MessageMetadata{
 		Mailbox: mbName,
 		To:      []*mail.Address{{Name: "", Address: "somebody@host"}},
 		From:    &mail.Address{Name: "", Address: "somebodyelse@host"},

pkg/storage/file/mbox.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"sync"
 
+	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/rs/zerolog/log"
 )
@@ -72,6 +73,10 @@ func (mb *mbox) removeMessage(id string) error {
 			msg = m
 			// Slice around message we are deleting
 			mb.messages = append(mb.messages[:i], mb.messages[i+1:]...)
+
+			// Emit deleted event.
+			mb.store.extHost.Events.AfterMessageDeleted.Emit(message.MakeMetadata(msg))
+
 			break
 		}
 	}

pkg/storage/mem/store.go

@@ -8,6 +8,8 @@ import (
 	"sync"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
 )
 
@@ -18,6 +20,7 @@ type Store struct {
 	cap      int           // Per-mailbox message cap.
 	incoming chan *msgDone // New messages for size enforcer.
 	remove   chan *msgDone // Remove deleted messages from size enforcer.
+	extHost  *extension.Host
 }
 
 type mbox struct {
@@ -31,10 +34,11 @@ type mbox struct {
 var _ storage.Store = &Store{}
 
 // New returns an emtpy memory store.
-func New(cfg config.Storage) (storage.Store, error) {
+func New(cfg config.Storage, extHost *extension.Host) (storage.Store, error) {
 	s := &Store{
-		boxes: make(map[string]*mbox),
+		boxes:   make(map[string]*mbox),
-		cap:   cfg.MailboxMsgCap,
+		cap:     cfg.MailboxMsgCap,
+		extHost: extHost,
 	}
 	if str, ok := cfg.Params["maxkb"]; ok {
 		maxKB, err := strconv.ParseInt(str, 10, 64)
@@ -140,16 +144,25 @@ func (s *Store) MarkSeen(mailbox, id string) error {
 
 // PurgeMessages deletes the contents of a mailbox.
 func (s *Store) PurgeMessages(mailbox string) error {
+	// Grab lock, copy messages, clear, and drop lock.
 	var messages map[string]*Message
 	s.withMailbox(mailbox, true, func(mb *mbox) {
 		messages = mb.messages
 		mb.messages = make(map[string]*Message)
 	})
-	if len(messages) > 0 && s.remove != nil {
+
+	// Process size/quota.
+	if s.remove != nil {
 		for _, m := range messages {
 			s.enforcerRemove(m)
 		}
 	}
+
+	// Emit delete events.
+	for _, m := range messages {
+		s.extHost.Events.AfterMessageDeleted.Emit(message.MakeMetadata(m))
+	}
+
 	return nil
 }
 
@@ -163,6 +176,11 @@ func (s *Store) removeMessage(mailbox, id string) *Message {
 			delete(mb.messages, id)
 		}
 	})
+
+	if m != nil {
+		s.extHost.Events.AfterMessageDeleted.Emit(message.MakeMetadata(m))
+	}
+
 	return m
 }
 

pkg/storage/mem/store_test.go

@@ -6,27 +6,32 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/test"
 )
 
 // TestSuite runs storage package test suite on file store.
 func TestSuite(t *testing.T) {
-	test.StoreSuite(t, func(conf config.Storage) (storage.Store, func(), error) {
+	test.StoreSuite(t,
-		s, _ := New(conf)
+		func(conf config.Storage, extHost *extension.Host) (storage.Store, func(), error) {
-		destroy := func() {}
+			s, _ := New(conf, extHost)
-		return s, destroy, nil
+			destroy := func() {}
-	})
+			return s, destroy, nil
+		})
 }
 
 // TestMessageList verifies the operation of the global message list: mem.Store.messages.
 func TestMaxSize(t *testing.T) {
+	extHost := extension.NewHost()
 	maxSize := int64(2048)
-	s, _ := New(config.Storage{Params: map[string]string{"maxkb": "2"}})
+	s, _ := New(config.Storage{Params: map[string]string{"maxkb": "2"}}, extHost)
 	boxes := []string{"alpha", "beta", "whiskey", "tango", "foxtrot"}
+
+	// Ensure capacity so we do not block population.
 	n := 10
-	// total := 50
 	sizeChan := make(chan int64, len(boxes))
+
 	// Populate mailboxes concurrently.
 	for _, mailbox := range boxes {
 		go func(mailbox string) {
@@ -38,11 +43,13 @@ func TestMaxSize(t *testing.T) {
 			sizeChan <- size
 		}(mailbox)
 	}
+
 	// Wait for sizes.
 	sentBytesTotal := int64(0)
 	for range boxes {
 		sentBytesTotal += <-sizeChan
 	}
+
 	// Calculate actual size.
 	gotSize := int64(0)
 	s.VisitMailboxes(func(messages []storage.Message) bool {
@@ -51,6 +58,7 @@ func TestMaxSize(t *testing.T) {
 		}
 		return true
 	})
+
 	// Verify state. Messages are ~75 bytes each.
 	if gotSize < 2048-75 {
 		t.Errorf("Got total size %v, want greater than: %v", gotSize, 2048-75)
@@ -58,6 +66,7 @@ func TestMaxSize(t *testing.T) {
 	if gotSize > maxSize {
 		t.Errorf("Got total size %v, want less than: %v", gotSize, maxSize)
 	}
+
 	// Purge all messages concurrently, testing for deadlocks.
 	wg := &sync.WaitGroup{}
 	wg.Add(len(boxes))

pkg/storage/retention.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"container/list"
+	"context"
 	"expvar"
 	"time"
 
@@ -50,7 +51,6 @@ func init() {
 
 // RetentionScanner looks for messages older than the configured retention period and deletes them.
 type RetentionScanner struct {
-	globalShutdown    chan bool // Closes when Inbucket needs to shut down
 	retentionShutdown chan bool // Closed after the scanner has shut down
 	ds                Store
 	retentionPeriod   time.Duration
@@ -61,10 +61,8 @@ type RetentionScanner struct {
 func NewRetentionScanner(
 	cfg config.Storage,
 	ds Store,
-	shutdownChannel chan bool,
 ) *RetentionScanner {
 	rs := &RetentionScanner{
-		globalShutdown:    shutdownChannel,
 		retentionShutdown: make(chan bool),
 		ds:                ds,
 		retentionPeriod:   cfg.RetentionPeriod,
@@ -76,20 +74,16 @@ func NewRetentionScanner(
 }
 
 // Start up the retention scanner if retention period > 0
-func (rs *RetentionScanner) Start() {
+func (rs *RetentionScanner) Start(ctx context.Context) {
+	slog := log.With().Str("module", "storage").Logger()
+
 	if rs.retentionPeriod <= 0 {
-		log.Info().Str("phase", "startup").Str("module", "storage").Msg("Retention scanner disabled")
+		slog.Info().Str("phase", "startup").Msg("Retention scanner disabled")
 		close(rs.retentionShutdown)
 		return
 	}
-	log.Info().Str("phase", "startup").Str("module", "storage").
+	slog.Info().Str("phase", "startup").Msgf("Retention configured for %v", rs.retentionPeriod)
-		Msgf("Retention configured for %v", rs.retentionPeriod)
-	go rs.run()
-}
 
-// run loops to kick off the scanner on the correct schedule
-func (rs *RetentionScanner) run() {
-	slog := log.With().Str("module", "storage").Logger()
 	start := time.Now()
 retentionLoop:
 	for {
@@ -99,19 +93,19 @@ retentionLoop:
 			dur := time.Minute - since
 			slog.Debug().Msgf("Retention scanner sleeping for %v", dur)
 			select {
-			case <-rs.globalShutdown:
+			case <-ctx.Done():
 				break retentionLoop
 			case <-time.After(dur):
 			}
 		}
 		// Kickoff scan
 		start = time.Now()
-		if err := rs.DoScan(); err != nil {
+		if err := rs.DoScan(ctx); err != nil {
 			slog.Error().Err(err).Msg("Error during retention scan")
 		}
 		// Check for global shutdown
 		select {
-		case <-rs.globalShutdown:
+		case <-ctx.Done():
 			break retentionLoop
 		default:
 		}
@@ -121,13 +115,14 @@ retentionLoop:
 }
 
 // DoScan does a single pass of all mailboxes looking for messages that can be purged.
-func (rs *RetentionScanner) DoScan() error {
+func (rs *RetentionScanner) DoScan(ctx context.Context) error {
 	slog := log.With().Str("module", "storage").Logger()
 	slog.Debug().Msg("Starting retention scan")
 	cutoff := time.Now().Add(-1 * rs.retentionPeriod)
+
+	// Loop over all mailboxes.
 	retained := 0
 	storeSize := int64(0)
-	// Loop over all mailboxes.
 	err := rs.ds.VisitMailboxes(func(messages []Message) bool {
 		for _, msg := range messages {
 			if msg.Date().Before(cutoff) {
@@ -145,7 +140,7 @@ func (rs *RetentionScanner) DoScan() error {
 			}
 		}
 		select {
-		case <-rs.globalShutdown:
+		case <-ctx.Done():
 			slog.Debug().Str("phase", "shutdown").Msg("Retention scan aborted due to shutdown")
 			return false
 		case <-time.After(rs.retentionSleep):
@@ -156,10 +151,12 @@ func (rs *RetentionScanner) DoScan() error {
 	if err != nil {
 		return err
 	}
+
 	// Update metrics
 	scanCompletedMillis.Set(time.Now().UnixNano() / 1000000)
 	expRetainedCurrent.Set(int64(retained))
 	expRetainedSize.Set(storeSize)
+
 	return nil
 }
 

pkg/storage/retention_test.go

@@ -1,11 +1,13 @@
 package storage_test
 
 import (
+	"context"
 	"fmt"
 	"testing"
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
 	"github.com/inbucket/inbucket/pkg/test"
@@ -13,6 +15,7 @@ import (
 
 func TestDoRetentionScan(t *testing.T) {
 	ds := test.NewStore()
+
 	// Mockup some different aged messages (num is in hours)
 	new1 := stubMessage("mb1", 0)
 	new2 := stubMessage("mb2", 1)
@@ -26,22 +29,26 @@ func TestDoRetentionScan(t *testing.T) {
 	ds.AddMessage(old3)
 	ds.AddMessage(new2)
 	ds.AddMessage(new3)
+
 	// Test 4 hour retention
 	cfg := config.Storage{
 		RetentionPeriod: 239 * time.Minute,
 		RetentionSleep:  0,
 	}
-	shutdownChan := make(chan bool)
+	ctx, cancel := context.WithCancel(context.Background())
-	rs := storage.NewRetentionScanner(cfg, ds, shutdownChan)
+	defer cancel()
-	if err := rs.DoScan(); err != nil {
+	rs := storage.NewRetentionScanner(cfg, ds)
+	if err := rs.DoScan(ctx); err != nil {
 		t.Error(err)
 	}
+
 	// Delete should not have been called on new messages
 	for _, m := range []storage.Message{new1, new2, new3} {
 		if ds.MessageDeleted(m) {
 			t.Errorf("Expected %v to be present, was deleted", m.ID())
 		}
 	}
+
 	// Delete should have been called once on old messages
 	for _, m := range []storage.Message{old1, old2, old3} {
 		if !ds.MessageDeleted(m) {
@@ -53,7 +60,7 @@ func TestDoRetentionScan(t *testing.T) {
 // stubMessage creates a message stub of a specific age
 func stubMessage(mailbox string, ageHours int) storage.Message {
 	return &message.Delivery{
-		Meta: message.Metadata{
+		Meta: event.MessageMetadata{
 			Mailbox: mailbox,
 			ID:      fmt.Sprintf("MSG[age=%vh]", ageHours),
 			Date:    time.Now().Add(time.Duration(ageHours*-1) * time.Hour),

pkg/storage/storage.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
 )
 
 var (
@@ -19,7 +20,7 @@ var (
 	ErrNotWritable = errors.New("Message not writable")
 
 	// Constructors tracks registered storage constructors
-	Constructors = make(map[string]func(config.Storage) (Store, error))
+	Constructors = make(map[string]func(config.Storage, *extension.Host) (Store, error))
 )
 
 // Store is the interface Inbucket uses to interact with storage implementations.
@@ -48,9 +49,9 @@ type Message interface {
 }
 
 // FromConfig creates an instance of the Store based on the provided configuration.
-func FromConfig(c config.Storage) (store Store, err error) {
+func FromConfig(c config.Storage, extHost *extension.Host) (store Store, err error) {
 	if cf := Constructors[c.Type]; cf != nil {
-		return cf(c)
+		return cf(c, extHost)
 	}
 	return nil, fmt.Errorf("unknown storage type configured: %q", c.Type)
 }

pkg/test/integration_test.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/msghub"
 	"github.com/inbucket/inbucket/pkg/policy"
@@ -32,6 +33,8 @@ const (
 	smtpHost    = "127.0.0.1:2500"
 )
 
+// TODO: Add suites for domain and full addressing modes.
+
 func TestSuite(t *testing.T) {
 	stopServer, err := startServer()
 	if err != nil {
@@ -46,6 +49,8 @@ func TestSuite(t *testing.T) {
 		{"basic", testBasic},
 		{"fullname", testFullname},
 		{"encodedHeader", testEncodedHeader},
+		{"ipv4Recipient", testIPv4Recipient},
+		{"ipv6Recipient", testIPv6Recipient},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, tc.test)
@@ -139,6 +144,64 @@ func testEncodedHeader(t *testing.T) {
 	goldiff.File(t, got, "testdata", "encodedheader.golden")
 }
 
+func testIPv4Recipient(t *testing.T) {
+	client, err := client.New(restBaseURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	from := "fromuser@inbucket.org"
+	to := []string{"ip4recipient@[192.168.123.123]"}
+	input := readTestData("no-to.txt")
+
+	// Send mail.
+	err = smtpclient.SendMail(smtpHost, nil, from, to, input)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Confirm receipt.
+	msg, err := client.GetMessage("ip4recipient", "latest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if msg == nil {
+		t.Errorf("Got nil message, wanted non-nil message.")
+	}
+
+	// Compare to golden.
+	got := formatMessage(msg)
+	goldiff.File(t, got, "testdata", "no-to-ipv4.golden")
+}
+
+func testIPv6Recipient(t *testing.T) {
+	client, err := client.New(restBaseURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	from := "fromuser@inbucket.org"
+	to := []string{"ip6recipient@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334]"}
+	input := readTestData("no-to.txt")
+
+	// Send mail.
+	err = smtpclient.SendMail(smtpHost, nil, from, to, input)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Confirm receipt.
+	msg, err := client.GetMessage("ip6recipient", "latest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if msg == nil {
+		t.Errorf("Got nil message, wanted non-nil message.")
+	}
+
+	// Compare to golden.
+	got := formatMessage(msg)
+	goldiff.File(t, got, "testdata", "no-to-ipv6.golden")
+}
+
 func formatMessage(m *client.Message) []byte {
 	b := &bytes.Buffer{}
 	fmt.Fprintf(b, "Mailbox: %v\n", m.Mailbox)
@@ -152,40 +215,46 @@ func formatMessage(m *client.Message) []byte {
 }
 
 func startServer() (func(), error) {
-	// TODO Refactor inbucket/main.go so we don't need to repeat all this here.
+	// TODO Move integration setup into lifecycle.
 	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr, NoColor: true})
+
+	extHost := extension.NewHost()
+
+	// Storage setup.
 	storage.Constructors["memory"] = mem.New
 	os.Clearenv()
 	conf, err := config.Process()
 	if err != nil {
 		return nil, err
 	}
-	rootCtx, rootCancel := context.WithCancel(context.Background())
+	svcCtx, svcCancel := context.WithCancel(context.Background())
-	shutdownChan := make(chan bool)
+	store, err := storage.FromConfig(conf.Storage, extHost)
-	store, err := storage.FromConfig(conf.Storage)
 	if err != nil {
-		rootCancel()
+		svcCancel()
 		return nil, err
 	}
-	msgHub := msghub.New(rootCtx, conf.Web.MonitorHistory)
+
+	// TODO Test should not pass with unstarted msghub.
 	addrPolicy := &policy.Addressing{Config: conf}
-	mmanager := &message.StoreManager{AddrPolicy: addrPolicy, Store: store, Hub: msgHub}
+	msgHub := msghub.New(conf.Web.MonitorHistory, extHost)
+	mmanager := &message.StoreManager{AddrPolicy: addrPolicy, Store: store, ExtHost: extHost}
+
 	// Start HTTP server.
 	webui.SetupRoutes(web.Router.PathPrefix("/serve/").Subrouter())
 	rest.SetupRoutes(web.Router.PathPrefix("/api/").Subrouter())
-	web.Initialize(conf, shutdownChan, mmanager, msgHub)
+	webServer := web.NewServer(conf, mmanager, msgHub)
-	go web.Start(rootCtx)
+	go webServer.Start(svcCtx, func() {})
-	// Start SMTP server.
-	smtpServer := smtp.NewServer(conf.SMTP, shutdownChan, mmanager, addrPolicy)
-	go smtpServer.Start(rootCtx)
 
-	// TODO Implmement an elegant way to determine server readiness.
+	// Start SMTP server.
+	smtpServer := smtp.NewServer(conf.SMTP, mmanager, addrPolicy, extHost)
+	go smtpServer.Start(svcCtx, func() {})
+
+	// TODO Use a readyFunc to determine server readiness.
 	time.Sleep(500 * time.Millisecond)
 
 	return func() {
 		// Shut everything down.
-		close(shutdownChan)
+		svcCancel()
-		rootCancel()
 		smtpServer.Drain()
 	}, nil
 }

pkg/test/manager.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/policy"
 	"github.com/inbucket/inbucket/pkg/storage"
@@ -42,14 +43,14 @@ func (m *ManagerStub) GetMessage(mailbox, id string) (*message.Message, error) {
 }
 
 // GetMetadata gets all the metadata for the specified mailbox.
-func (m *ManagerStub) GetMetadata(mailbox string) ([]*message.Metadata, error) {
+func (m *ManagerStub) GetMetadata(mailbox string) ([]*event.MessageMetadata, error) {
 	if mailbox == "messageserr" {
 		return nil, errors.New("internal error")
 	}
 	messages := m.mailboxes[mailbox]
-	metas := make([]*message.Metadata, len(messages))
+	metas := make([]*event.MessageMetadata, len(messages))
 	for i, msg := range messages {
-		metas[i] = &msg.Metadata
+		metas[i] = &msg.MessageMetadata
 	}
 	return metas, nil
 }
@@ -69,7 +70,7 @@ func (m *ManagerStub) MarkSeen(mailbox, id string) error {
 	}
 	for _, msg := range m.mailboxes[mailbox] {
 		if msg.ID == id {
-			msg.Metadata.Seen = true
+			msg.MessageMetadata.Seen = true
 			return nil
 		}
 	}

pkg/test/storage_suite.go

@@ -10,18 +10,23 @@ import (
 	"time"
 
 	"github.com/inbucket/inbucket/pkg/config"
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/inbucket/inbucket/pkg/extension/event"
 	"github.com/inbucket/inbucket/pkg/message"
 	"github.com/inbucket/inbucket/pkg/storage"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // StoreFactory returns a new store for the test suite.
-type StoreFactory func(config.Storage) (store storage.Store, destroy func(), err error)
+type StoreFactory func(
+	config.Storage, *extension.Host) (store storage.Store, destroy func(), err error)
 
 // StoreSuite runs a set of general tests on the provided Store.
 func StoreSuite(t *testing.T, factory StoreFactory) {
 	testCases := []struct {
 		name string
-		test func(*testing.T, storage.Store)
+		test func(*testing.T, storage.Store, *extension.Host)
 		conf config.Storage
 	}{
 		{"metadata", testMetadata, config.Storage{}},
@@ -39,18 +44,19 @@ func StoreSuite(t *testing.T, factory StoreFactory) {
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			store, destroy, err := factory(tc.conf)
+			extHost := extension.NewHost()
+			store, destroy, err := factory(tc.conf, extHost)
 			if err != nil {
 				t.Fatal(err)
 			}
-			tc.test(t, store)
+			tc.test(t, store, extHost)
 			destroy()
 		})
 	}
 }
 
 // testMetadata verifies message metadata is stored and retrieved correctly.
-func testMetadata(t *testing.T, store storage.Store) {
+func testMetadata(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "testmailbox"
 	from := &mail.Address{Name: "From Person", Address: "from@person.com"}
 	to := []*mail.Address{
@@ -61,7 +67,7 @@ func testMetadata(t *testing.T, store storage.Store) {
 	subject := "fantastic test subject line"
 	content := "doesn't matter"
 	delivery := &message.Delivery{
-		Meta: message.Metadata{
+		Meta: event.MessageMetadata{
 			// ID and Size will be determined by the Store.
 			Mailbox: mailbox,
 			From:    from,
@@ -117,7 +123,7 @@ func testMetadata(t *testing.T, store storage.Store) {
 }
 
 // testContent generates some binary content and makes sure it is correctly retrieved.
-func testContent(t *testing.T, store storage.Store) {
+func testContent(t *testing.T, store storage.Store, extHost *extension.Host) {
 	content := make([]byte, 5000)
 	for i := 0; i < len(content); i++ {
 		content[i] = byte(i % 256)
@@ -130,7 +136,7 @@ func testContent(t *testing.T, store storage.Store) {
 	date := time.Now()
 	subject := "fantastic test subject line"
 	delivery := &message.Delivery{
-		Meta: message.Metadata{
+		Meta: event.MessageMetadata{
 			// ID and Size will be determined by the Store.
 			Mailbox: mailbox,
 			From:    from,
@@ -168,14 +174,13 @@ func testContent(t *testing.T, store storage.Store) {
 		}
 		if errors > 5 {
 			t.Fatalf("Too many content errors, aborting test.")
-			break
 		}
 	}
 }
 
 // testDeliveryOrder delivers several messages to the same mailbox, meanwhile querying its contents
 // with a new GetMessages call each cycle.
-func testDeliveryOrder(t *testing.T, store storage.Store) {
+func testDeliveryOrder(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "fred"
 	subjects := []string{"alpha", "bravo", "charlie", "delta", "echo"}
 	for i, subj := range subjects {
@@ -195,7 +200,7 @@ func testDeliveryOrder(t *testing.T, store storage.Store) {
 
 // testLatest delivers several messages to the same mailbox, and confirms the id `latest` returns
 // the last message sent.
-func testLatest(t *testing.T, store storage.Store) {
+func testLatest(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "fred"
 	subjects := []string{"alpha", "bravo", "charlie", "delta", "echo"}
 	for _, subj := range subjects {
@@ -217,14 +222,14 @@ func testLatest(t *testing.T, store storage.Store) {
 }
 
 // testNaming ensures the store does not enforce local part mailbox naming.
-func testNaming(t *testing.T, store storage.Store) {
+func testNaming(t *testing.T, store storage.Store, extHost *extension.Host) {
 	DeliverToStore(t, store, "fred@fish.net", "disk #27", time.Now())
 	GetAndCountMessages(t, store, "fred", 0)
 	GetAndCountMessages(t, store, "fred@fish.net", 1)
 }
 
 // testSize verifies message content size metadata values.
-func testSize(t *testing.T, store storage.Store) {
+func testSize(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "fred"
 	subjects := []string{"a", "br", "much longer than the others"}
 	sentIds := make([]string, len(subjects))
@@ -248,7 +253,7 @@ func testSize(t *testing.T, store storage.Store) {
 }
 
 // testSeen verifies a message can be marked as seen.
-func testSeen(t *testing.T, store storage.Store) {
+func testSeen(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "lisa"
 	id1, _ := DeliverToStore(t, store, mailbox, "whatever", time.Now())
 	id2, _ := DeliverToStore(t, store, mailbox, "hello?", time.Now())
@@ -284,22 +289,24 @@ func testSeen(t *testing.T, store storage.Store) {
 }
 
 // testDelete creates and deletes some messages.
-func testDelete(t *testing.T, store storage.Store) {
+func testDelete(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "fred"
 	subjects := []string{"alpha", "bravo", "charlie", "delta", "echo"}
 	for _, subj := range subjects {
 		DeliverToStore(t, store, mailbox, subj, time.Now())
 	}
 	msgs := GetAndCountMessages(t, store, mailbox, len(subjects))
+
+	// Subscribe to events.
+	eventListener := extHost.Events.AfterMessageDeleted.AsyncTestListener("test", 2)
+
 	// Delete a couple messages.
-	err := store.RemoveMessage(mailbox, msgs[1].ID())
+	deleteIDs := []string{msgs[1].ID(), msgs[3].ID()}
-	if err != nil {
+	for _, id := range deleteIDs {
-		t.Fatal(err)
+		err := store.RemoveMessage(mailbox, id)
-	}
+		require.NoError(t, err)
-	err = store.RemoveMessage(mailbox, msgs[3].ID())
-	if err != nil {
-		t.Fatal(err)
 	}
+
 	// Confirm deletion.
 	subjects = []string{"alpha", "charlie", "echo"}
 	msgs = GetAndCountMessages(t, store, mailbox, len(subjects))
@@ -309,6 +316,17 @@ func testDelete(t *testing.T, store storage.Store) {
 			t.Errorf("Got subject %q, want %q", got, want)
 		}
 	}
+
+	// Capture events and check correct IDs were emitted.
+	ev1, err := eventListener()
+	require.NoError(t, err)
+	ev2, err := eventListener()
+	require.NoError(t, err)
+	eventIDs := []string{ev1.ID, ev2.ID}
+	for _, id := range deleteIDs {
+		assert.Contains(t, eventIDs, id)
+	}
+
 	// Try appending one more.
 	DeliverToStore(t, store, mailbox, "foxtrot", time.Now())
 	subjects = []string{"alpha", "charlie", "echo", "foxtrot"}
@@ -322,23 +340,40 @@ func testDelete(t *testing.T, store storage.Store) {
 }
 
 // testPurge makes sure mailboxes can be purged.
-func testPurge(t *testing.T, store storage.Store) {
+func testPurge(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "fred"
 	subjects := []string{"alpha", "bravo", "charlie", "delta", "echo"}
+
+	// Subscribe to events.
+	eventListener := extHost.Events.AfterMessageDeleted.AsyncTestListener("test", len(subjects))
+
+	// Populate mailbox.
 	for _, subj := range subjects {
 		DeliverToStore(t, store, mailbox, subj, time.Now())
 	}
 	GetAndCountMessages(t, store, mailbox, len(subjects))
+
 	// Purge and verify.
 	err := store.PurgeMessages(mailbox)
-	if err != nil {
+	require.NoError(t, err)
-		t.Fatal(err)
-	}
 	GetAndCountMessages(t, store, mailbox, 0)
+
+	// Confirm events emitted.
+	gotEvents := []*event.MessageMetadata{}
+	for range subjects {
+		ev, err := eventListener()
+		if err != nil {
+			t.Error(err)
+			break
+		}
+		gotEvents = append(gotEvents, ev)
+	}
+	assert.Equal(t, len(subjects), len(gotEvents),
+		"expected delete event for each message in mailbox")
 }
 
 // testMsgCap verifies the message cap is enforced.
-func testMsgCap(t *testing.T, store storage.Store) {
+func testMsgCap(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mbCap := 10
 	mailbox := "captain"
 	for i := 0; i < 20; i++ {
@@ -365,7 +400,7 @@ func testMsgCap(t *testing.T, store storage.Store) {
 }
 
 // testNoMsgCap verfies a cap of 0 is not enforced.
-func testNoMsgCap(t *testing.T, store storage.Store) {
+func testNoMsgCap(t *testing.T, store storage.Store, extHost *extension.Host) {
 	mailbox := "captain"
 	for i := 0; i < 20; i++ {
 		subj := fmt.Sprintf("subject %v", i)
@@ -376,7 +411,7 @@ func testNoMsgCap(t *testing.T, store storage.Store) {
 
 // testVisitMailboxes creates some mailboxes and confirms the VisitMailboxes method visits all of
 // them.
-func testVisitMailboxes(t *testing.T, ds storage.Store) {
+func testVisitMailboxes(t *testing.T, ds storage.Store, extHost *extension.Host) {
 	boxes := []string{"abby", "bill", "christa", "donald", "evelyn"}
 	for _, name := range boxes {
 		DeliverToStore(t, ds, name, "Old Message", time.Now().Add(-24*time.Hour))
@@ -409,7 +444,7 @@ func DeliverToStore(
 	date time.Time,
 ) (string, int64) {
 	t.Helper()
-	meta := message.Metadata{
+	meta := event.MessageMetadata{
 		Mailbox: mailbox,
 		To:      []*mail.Address{{Name: "Some Body", Address: "somebody@host"}},
 		From:    &mail.Address{Name: "Some B. Else", Address: "somebodyelse@host"},

pkg/test/testdata/no-to-ipv4.golden

@@ -0,0 +1,12 @@
+Mailbox: ip4recipient
+From: <fromuser@inbucket.org>
+To: [<ip4recipient@[192.168.123.123]>]
+Subject: basic subject
+Size: 198
+
+BODY TEXT:
+No-To message.
+
+
+BODY HTML:
+

pkg/test/testdata/no-to-ipv6.golden

@@ -0,0 +1,12 @@
+Mailbox: ip6recipient
+From: <fromuser@inbucket.org>
+To: [<ip6recipient@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334]>]
+Subject: basic subject
+Size: 227
+
+BODY TEXT:
+No-To message.
+
+
+BODY HTML:
+

pkg/test/testdata/no-to.txt

@@ -0,0 +1,4 @@
+From: fromuser@inbucket.org
+Subject: basic subject
+
+No-To message.

shell.nix

@@ -1,19 +1,38 @@
-with import <nixpkgs> {};
+{ pkgs ? import <nixpkgs> { } }:
-stdenv.mkDerivation rec {
+let
-  name = "env";
+  scripts = {
-  env = buildEnv { name = name; paths = buildInputs; };
+    # Quick test script.
-  buildInputs = [
+    qt = pkgs.writeScriptBin "qt" ''
+      # Builds & starts inbucket, then sends it some test mail.
+
+      make build test inbucket || exit
+      (sleep 3; etc/swaks-tests/run-tests.sh >/dev/null) &
+      env INBUCKET_LOGLEVEL=debug ./inbucket
+    '';
+  };
+in
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    act
     dpkg
+    delve
     elmPackages.elm
     elmPackages.elm-analyse
     elmPackages.elm-format
     elmPackages.elm-json
     elmPackages.elm-language-server
     elmPackages.elm-test
-    go
+    go_1_18
     golint
-    nodejs-14_x
+    gopls
+    nodejs-16_x
+    nodePackages.yarn
     rpm
     swaks
+
+    scripts.qt
   ];
+
+  # Prevents launch errors with delve debugger.
+  hardeningDisable = [ "fortify" ];
 }

ui/.parcelrc

@@ -0,0 +1,4 @@
+{
+  "extends": "@parcel/config-default",
+  "namers": [ "parcel-namer-rewrite" ]
+}

ui/.proxyrc.json

@@ -0,0 +1,12 @@
+{
+  "/api": {
+    "target": "http://localhost:9000",
+    "ws": true
+  },
+  "/debug": {
+    "target": "http://localhost:9000"
+  },
+  "/serve": {
+    "target": "http://localhost:9000"
+  }
+}

ui/README.md

@@ -11,9 +11,8 @@ One time setup (assuming [Node.js] is already installed):
 
 ```
 cd $INBUCKET/ui
-npm i elm -g
+yarn install
-npm i
+yarn build
-npm run build
 ```
 
 This will the create `node_modules`, `elm-stuff`, and `dist` directories.
@@ -30,15 +29,16 @@ Inbucket will start, with HTTP listening on port 9000.  You may verify the web
 UI is functional if this is your first time building Inbucket, but your dev/test
 cycle should favor the development server below.
 
-### Terminal 2: webpack development server
+### Terminal 2: parcel development server
 
 ```
 cd $INBUCKET/ui
-npm run dev
+yarn start
 ```
 
-npm will start a development HTTP server listening on port 3000.  You should use
+yarn will start a development HTTP server listening on port 1234.  You should
-this server for UI development, as it features hot reload and the Elm debugger.
+use this server for UI development, as it features hot reload and the Elm
+debugger.
 
 [Elm]:            https://elm-lang.org
 [Node.js]:        https://nodejs.org

ui/package.json

@@ -4,30 +4,29 @@
   "license": "MIT",
   "private": true,
   "scripts": {
-    "clean": "rm -rf dist elm-stuff",
+    "build": "parcel build --public-url ./",
-    "build": "webpack --mode production",
+    "start": "parcel --hmr-port 1235 src/index-dev.html",
-    "watch": "webpack --mode development --watch",
+    "clean": "rm -rf .parcel-cache dist elm-stuff"
-    "dev": "webpack-dev-server --mode development --port 3000 --hot --watch",
-    "errors": "webpack --mode development --display-error-details"
   },
-  "dependencies": {
+  "source": "src/index.html",
-    "opensans-npm-webfont": "^1.0.0"
+  "parcel-namer-rewrite": {
+    "rules": {
+      "(.*)\\.(css|js|json|eot|png|svg|ttf|webmanifest|woff|woff2)": "static/$1{.hash}.$2"
+    }
   },
+  "browserslist": "defaults",
+  "dependencies": {},
   "devDependencies": {
-    "@babel/core": "^7.14.8",
-    "@babel/preset-env": "^7.14.8",
     "@fortawesome/fontawesome-free": "^5.15.3",
+    "@parcel/packager-raw-url": "2.4.1",
+    "@parcel/transformer-elm": "^2.2.1",
+    "@parcel/transformer-webmanifest": "2.4.1",
     "@webcomponents/webcomponentsjs": "^2.5.0",
-    "babel-loader": "^8.2.2",
+    "opensans-npm-webfont": "^1.0.0",
-    "css-loader": "^4.3.0",
+    "parcel": "^2.4.1",
-    "elm-hot-webpack-loader": "^1.1.8",
+    "parcel-namer-rewrite": "^2.0.0-rc.2"
-    "elm-webpack-loader": "^7.0.1",
+  },
-    "file-loader": "^6.2.0",
+  "optionalDependencies": {
-    "html-webpack-plugin": "^4.5.2",
+    "elm": "^0.19.1-5"
-    "node-elm-compiler": "^5.0.6",
-    "style-loader": "^1.3.0",
-    "webpack": "^4.46.0",
-    "webpack-cli": "^3.3.12",
-    "webpack-dev-server": "^3.11.2"
   }
 }

ui/src/Api.elm

@@ -127,7 +127,7 @@ markMessageSeen session msg mailboxName id =
 
 monitorUri : Session -> String
 monitorUri session =
-    apiV1Url session [ "monitor", "messages" ]
+    apiV2Url session [ "monitor", "messages" ]
 
 
 purgeMailbox : Session -> HttpResult msg -> String -> Cmd msg
@@ -135,14 +135,24 @@ purgeMailbox session msg mailboxName =
     HttpUtil.delete msg (apiV1Url session [ "mailbox", mailboxName ])
 
 
+apiV1Url : Session -> List String -> String
+apiV1Url =
+    apiUrl "v1"
+
+
+apiV2Url : Session -> List String -> String
+apiV2Url =
+    apiUrl "v2"
+
+
 {-| Builds a public REST API URL (see wiki).
 -}
-apiV1Url : Session -> List String -> String
+apiUrl : String -> Session -> List String -> String
-apiV1Url session elements =
+apiUrl version session elements =
     Url.Builder.absolute
         (List.concat
             [ splitBasePath session.config.basePath
-            , [ "api", "v1" ]
+            , [ "api", version ]
             , elements
             ]
         )

ui/src/Data/MonitorEvent.elm

@@ -0,0 +1,44 @@
+module Data.MonitorEvent exposing (MessageID, MonitorEvent(..), decoder)
+
+import Data.MessageHeader as MessageHeader exposing (MessageHeader)
+import Json.Decode exposing (Decoder, andThen, fail, field, string, succeed)
+import Json.Decode.Pipeline exposing (required)
+
+
+type alias MessageID =
+    { mailbox : String
+    , id : String
+    }
+
+
+type MonitorEvent
+    = MessageStored MessageHeader
+    | MessageDeleted MessageID
+
+
+decoder : Decoder MonitorEvent
+decoder =
+    field "variant" string
+        |> andThen variantDecoder
+
+
+variantDecoder : String -> Decoder MonitorEvent
+variantDecoder variant =
+    case variant of
+        "message-deleted" ->
+            succeed MessageDeleted
+                |> required "identifier" messageIdDecoder
+
+        "message-stored" ->
+            succeed MessageStored
+                |> required "header" MessageHeader.decoder
+
+        unknown ->
+            fail <| "Unknown variant: " ++ unknown
+
+
+messageIdDecoder : Decoder MessageID
+messageIdDecoder =
+    succeed MessageID
+        |> required "mailbox" string
+        |> required "id" string

ui/src/Page/Monitor.elm

@@ -1,7 +1,8 @@
 module Page.Monitor exposing (Model, Msg, init, update, view)
 
 import Api
-import Data.MessageHeader as MessageHeader exposing (MessageHeader)
+import Data.MessageHeader exposing (MessageHeader)
+import Data.MonitorEvent as MonitorEvent
 import Data.Session exposing (Session)
 import DateFormat as DF
 import Effect exposing (Effect)
@@ -68,11 +69,23 @@ update msg model =
             ( { model | connected = False }, Effect.none )
 
         MessageReceived value ->
-            case D.decodeValue (MessageHeader.decoder |> D.at [ "detail" ]) value of
+            case D.decodeValue (MonitorEvent.decoder |> D.at [ "detail" ]) value of
-                Ok header ->
+                Ok event ->
-                    ( { model | messages = header :: List.take 500 model.messages }
+                    case event of
-                    , Effect.none
+                        MonitorEvent.MessageDeleted deleted ->
-                    )
+                            ( { model
+                                | messages =
+                                    List.filter
+                                        (\x -> x.mailbox /= deleted.mailbox || x.id /= deleted.id)
+                                        model.messages
+                              }
+                            , Effect.none
+                            )
+
+                        MonitorEvent.MessageStored header ->
+                            ( { model | messages = header :: List.take 500 model.messages }
+                            , Effect.none
+                            )
 
                 Err err ->
                     let

ui/src/index-dev.html

@@ -1,15 +1,20 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-  <!-- This index file will be served by the webpack development server. -->
+  <!-- This index file will be served by the development server. -->
   <base href="/">
   <meta charset="utf-8">
   <meta http-equiv="x-ua-compatible" content="ie=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
   <meta name="theme-color" content="#000000">
-  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
+  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
-  <meta http-equiv="Pragma" content="no-cache" />
+  <meta http-equiv="Pragma" content="no-cache">
-  <meta http-equiv="Expires" content="0" />
+  <meta http-equiv="Expires" content="0">
+  <link rel="stylesheet" href="./main.css">
+  <link rel="stylesheet" href="./navbar.css">
+  <link rel="stylesheet" href="./mailbox.css">
+  <link rel="icon" type="image/png" href="./favicon.png">
+  <link rel="manifest" href="./manifest.json">
   <title>Inbucket</title>
 </head>
 <body>
@@ -17,5 +22,6 @@
     You need to enable JavaScript to run this app.
   </noscript>
   <div id="root"></div>
+  <script type="module" src="index.js"></script>
 </body>
 </html>

ui/src/index.html

@@ -6,9 +6,14 @@
   <meta http-equiv="x-ua-compatible" content="ie=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
   <meta name="theme-color" content="#000000">
-  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
+  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
-  <meta http-equiv="Pragma" content="no-cache" />
+  <meta http-equiv="Pragma" content="no-cache">
-  <meta http-equiv="Expires" content="0" />
+  <meta http-equiv="Expires" content="0">
+  <link rel="stylesheet" href="./main.css">
+  <link rel="stylesheet" href="./navbar.css">
+  <link rel="stylesheet" href="./mailbox.css">
+  <link rel="icon" type="image/png" href="./favicon.png">
+  <link rel="manifest" href="./manifest.json">
   <title>Inbucket</title>
 </head>
 <body>
@@ -16,5 +21,6 @@
     You need to enable JavaScript to run this app.
   </noscript>
   <div id="root"></div>
+  <script type="module" src="index.js"></script>
 </body>
 </html>

ui/src/index.js

@@ -1,6 +1,3 @@
-import './main.css'
-import './mailbox.css'
-import './navbar.css'
 import '@fortawesome/fontawesome-free/css/all.css'
 import '@webcomponents/webcomponentsjs/webcomponents-bundle'
 import 'opensans-npm-webfont'

ui/webpack.config.js

@@ -1,84 +0,0 @@
-const HtmlWebpackPlugin = require('html-webpack-plugin')
-const webpack = require('webpack')
-
-module.exports = (env, argv) => {
-  const production = argv.mode === 'production'
-  const config = {
-    output: {
-      filename: 'static/[name].[hash:8].js',
-      publicPath: '',
-    },
-    module: {
-      rules: [
-        {
-          test: /\.js$/,
-          exclude: [/elm-stuff/, /node_modules/],
-          loader: 'babel-loader',
-          query: {
-            presets: [
-              '@babel/preset-env',
-            ],
-          },
-        },
-        {
-          test: /\.elm$/,
-          exclude: [/elm-stuff/, /node_modules/],
-          use: [
-            { loader: 'elm-hot-webpack-loader' },
-            {
-              loader: 'elm-webpack-loader',
-              options: {
-                debug: !production,
-                optimize: production,
-              },
-            },
-          ],
-        },
-        {
-          test: /\.css$/,
-          loader: ['style-loader', 'css-loader'],
-        },
-        {
-          test: /\.(eot|svg|ttf|woff|woff2)$/,
-          loader: 'file-loader',
-          options: {
-            name: 'static/[name].[hash:8].[ext]',
-          },
-        },
-      ]
-    },
-    plugins: [
-      new HtmlWebpackPlugin({
-        template: 'public/index.html',
-        favicon: 'public/favicon.png',
-      }),
-      new HtmlWebpackPlugin({
-        filename: 'index-dev.html',
-        template: 'public/index-dev.html',
-        favicon: 'public/favicon.png',
-      }),
-    ],
-    devServer: {
-      historyApiFallback: {
-        index: '/index-dev.html',
-      },
-      index: 'index-dev.html',
-      inline: true,
-      overlay: true,
-      open: true,
-      proxy: [{
-        context: ['/api', '/debug', '/serve'],
-        target: 'http://localhost:9000',
-        ws: true,
-      }],
-      stats: { colors: true },
-      watchOptions: {
-        ignored: /node_modules/,
-      },
-    },
-  }
-  if (argv.hot) {
-    config.plugins.push(new webpack.HotModuleReplacementPlugin())
-  }
-  return config
-}