smtp: Don't require MIME headers for metadata

This was a regression, will again fall back to MAIL FROM/RCPT TO data.

pkg/server/smtp/handler.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"net/mail"
 	"regexp"
 	"strconv"
 	"strings"
@@ -408,13 +409,14 @@ func (ss *Session) deliverMessage(recip *policy.Recipient, content []byte) (ok b
 	}
 	from, err := env.AddressList("From")
 	if err != nil {
-		ss.logError("Failed to get From address: %v", err)
+		from = []*mail.Address{{Address: ss.from}}
-		return false
 	}
 	to, err := env.AddressList("To")
 	if err != nil {
-		ss.logError("Failed to get To addresses: %v", err)
+		to = make([]*mail.Address, len(ss.recipients))
-		return false
+		for i, torecip := range ss.recipients {
+			to[i] = &torecip.Address
+		}
 	}
 	// Generate Received header.
 	stamp := time.Now().Format(timeStampFormat)

pkg/server/smtp/handler_test.go

@@ -200,7 +200,7 @@ func TestMailState(t *testing.T) {
 		{"MAIL FROM:<john@gmail.com>", 250},
 		{"RCPT TO:<u1@gmail.com>", 250},
 		{"DATA", 354},
-		{".", 451},
+		{".", 250},
 	}
 	if err := playSession(t, server, script); err != nil {
 		t.Error(err)
@@ -247,7 +247,6 @@ func TestDataState(t *testing.T) {
 	pipe := setupSMTPSession(server)
 	c := textproto.NewConn(pipe)
 
-	// Get us into DATA state
 	if code, _, err := c.ReadCodeLine(220); err != nil {
 		t.Errorf("Expected a 220 greeting, got %v", code)
 	}
@@ -274,6 +273,33 @@ Hi!
 		t.Errorf("Expected a 250 greeting, got %v", code)
 	}
 
+	// Test with no useful headers.
+	pipe = setupSMTPSession(server)
+	c = textproto.NewConn(pipe)
+	if code, _, err := c.ReadCodeLine(220); err != nil {
+		t.Errorf("Expected a 220 greeting, got %v", code)
+	}
+	script = []scriptStep{
+		{"HELO localhost", 250},
+		{"MAIL FROM:<john@gmail.com>", 250},
+		{"RCPT TO:<u1@gmail.com>", 250},
+		{"DATA", 354},
+	}
+	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?
+`
+	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)
+	}
+
 	if t.Failed() {
 		// Wait for handler to finish logging
 		time.Sleep(2 * time.Second)