diff --git a/smtpd/datastore.go b/smtpd/datastore.go
index 79bde52..f2ec9e2 100644
--- a/smtpd/datastore.go
+++ b/smtpd/datastore.go
@@ -17,6 +17,7 @@ import (
 
 type DataStore interface {
 	MailboxFor(emailAddress string) (Mailbox, error)
+	AllMailboxes() ([]Mailbox, error)
 }
 
 type Mailbox interface {
@@ -95,6 +96,11 @@ func (ds *FileDataStore) MailboxFor(emailAddress string) (Mailbox, error) {
 	return &FileMailbox{store: ds, name: name, dirName: dir, path: path}, nil
 }
 
+// AllMailboxes returns a slice with all Mailboxes
+func (ds *FileDataStore) AllMailboxes() ([]Mailbox, error) {
+	return nil, nil
+}
+
 // A Mailbox manages the mail for a specific user and correlates to a particular
 // directory on disk.
 type FileMailbox struct {
diff --git a/smtpd/retention.go b/smtpd/retention.go
index 89e8b60..ddfe260 100644
--- a/smtpd/retention.go
+++ b/smtpd/retention.go
@@ -1,12 +1,37 @@
 package smtpd
 
 import (
-	//"github.com/jhillyerd/inbucket/config"
-	//"github.com/jhillyerd/inbucket/log"
-//	"io/ioutil"
+	"github.com/jhillyerd/inbucket/log"
+	"time"
 )
 
 // retentionScan does a single pass of all mailboxes looking for messages that can be purged
-func retentionScan(ds *DataStore) {
+func retentionScan(ds DataStore, maxAge time.Duration, sleep time.Duration) error {
+	log.Trace("Starting retention scan")
+	cutoff := time.Now().Add(-1 * maxAge)
+	mboxes, err := ds.AllMailboxes()
+	if err != nil {
+		return err
+	}
 
+	for _, mb := range mboxes {
+		messages, err := mb.GetMessages()
+		if err != nil {
+			return err
+		}
+		for _, msg := range messages {
+			if msg.Date().Before(cutoff) {
+				log.Trace("Purging expired message %v", msg.Id())
+				err = msg.Delete()
+				if err != nil {
+					// Log but don't abort
+					log.Error("Failed to purge message %v: %v", msg.Id(), err)
+				}
+			}
+		}
+		// Sleep after completing a mailbox
+		time.Sleep(sleep)
+	}
+
+	return nil
 }
diff --git a/smtpd/retention_test.go b/smtpd/retention_test.go
index c842472..2d39fdd 100644
--- a/smtpd/retention_test.go
+++ b/smtpd/retention_test.go
@@ -2,123 +2,160 @@ package smtpd
 
 import (
 	"fmt"
-	"github.com/stretchrcom/testify/assert"
 	"github.com/stretchrcom/testify/mock"
-	"io/ioutil"
-	"os"
-	"path/filepath"
+	"net/mail"
 	"testing"
 	"time"
 )
 
+func TestSometing(t *testing.T) {
+	// Create mock objects
+	mds := &MockDataStore{}
+
+	mb1 := &MockMailbox{}
+	mb2 := &MockMailbox{}
+	mb3 := &MockMailbox{}
+
+	// Mockup some different aged messages (num is in hours)
+	new1 := mockMessage(0)
+	new2 := mockMessage(1)
+	new3 := mockMessage(2)
+	old1 := mockMessage(4)
+	old2 := mockMessage(12)
+	old3 := mockMessage(24)
+
+	// First it should ask for all mailboxes
+	mds.On("AllMailboxes").Return([]Mailbox{mb1, mb2, mb3}, nil)
+
+	// Then for all messages on each box
+	mb1.On("GetMessages").Return([]Message{new1, old1, old2}, nil)
+	mb2.On("GetMessages").Return([]Message{old3, new2}, nil)
+	mb3.On("GetMessages").Return([]Message{new3}, nil)
+
+	// Test 4 hour retention
+	retentionScan(mds, 4*time.Hour, 0)
+
+	// Check our assertions
+	mds.AssertExpectations(t)
+	mb1.AssertExpectations(t)
+	mb2.AssertExpectations(t)
+	mb3.AssertExpectations(t)
+
+	// Delete should not have been called on new messages
+	new1.AssertNotCalled(t, "Delete")
+	new2.AssertNotCalled(t, "Delete")
+	new3.AssertNotCalled(t, "Delete")
+
+	// Delete should have been called once on old messages
+	old1.AssertNumberOfCalls(t, "Delete", 1)
+	old2.AssertNumberOfCalls(t, "Delete", 1)
+	old3.AssertNumberOfCalls(t, "Delete", 1)
+}
+
+// Make a MockMessage of a specific age
+func mockMessage(ageHours int) *MockMessage {
+	msg := &MockMessage{}
+	msg.On("Id").Return(fmt.Sprintf("MSG[age=%vh]", ageHours))
+	msg.On("Date").Return(time.Now().Add(time.Duration(ageHours*-1) * time.Hour))
+	msg.On("Delete").Return(nil)
+	return msg
+}
+
+// Mock DataStore object
 type MockDataStore struct {
 	mock.Mock
-	path     string
-	mailPath string
 }
 
-var names = []string{"abby", "bill", "christa", "donald", "evelyn"}
-
-func TestSometing(t *testing.T) {
-	ds := setupDataStore()
-	fmt.Println(ds)
-	//defer teardownDataStore(ds)
-
-	assert.Equal(t, true, true)
+func (m *MockDataStore) MailboxFor(name string) (Mailbox, error) {
+	return nil, nil
 }
 
-// setupDataStore will build the following structure in a temporary
-// directory:
-//
-// /tmp/inbucket?????????
-// └── mail
-//     ├── 53e
-//     │   └── 53e11e
-//     │       └── 53e11eb7b24cc39e33733a0ff06640f1b39425ea
-//     │           ├── 20121024T164239-0000.gob
-//     │           ├── 20121024T164239-0000.raw
-//     │           ├── 20121025T164239-0000.gob
-//     │           └── 20121025T164239-0000.raw
-//     ├── 60c
-//     │   └── 60c596
-//     │       └── 60c5963a56da1425f133d28166ca4fe70dcb25f5
-//     │           ├── 20121024T164239-0000.gob
-//     │           ├── 20121024T164239-0000.raw
-//     │           ├── 20121025T164239-0000.gob
-//     │           └── 20121025T164239-0000.raw
-//     ├── 88d
-//     │   └── 88db92
-//     │       └── 88db9292c772b38311e1778f6f6b18216443abf0
-//     │           ├── 20121024T164239-0000.gob
-//     │           ├── 20121024T164239-0000.raw
-//     │           ├── 20121025T164239-0000.gob
-//     │           └── 20121025T164239-0000.raw
-//     ├── c69
-//     │   └── c692d6
-//     │       └── c692d6a10598e0a801576fdd4ecf3c37e45bfbc4
-//     │           ├── 20121024T164239-0000.gob
-//     │           ├── 20121024T164239-0000.raw
-//     │           ├── 20121025T164239-0000.gob
-//     │           └── 20121025T164239-0000.raw
-//     └── e76
-//         └── e76cef
-//             └── e76ceff3c47adb10f62b1acd7109f88fbd5e9ca7
-//                 ├── 20121024T164239-0000.gob
-//                 ├── 20121024T164239-0000.raw
-//                 ├── 20121025T164239-0000.gob
-//                 └── 20121025T164239-0000.raw
-func setupDataStore() *FileDataStore {
-	// Build fake SMTP message for delivery
-	testMsg := make([]byte, 0, 300)
-	testMsg = append(testMsg, []byte("To: somebody@host\r\n")...)
-	testMsg = append(testMsg, []byte("From: somebodyelse@host\r\n")...)
-	testMsg = append(testMsg, []byte("Subject: test message\r\n")...)
-	testMsg = append(testMsg, []byte("\r\n")...)
-	testMsg = append(testMsg, []byte("Test Body\r\n")...)
-
-	path, err := ioutil.TempDir("", "inbucket")
-	if err != nil {
-		panic(err)
-	}
-	mailPath := filepath.Join(path, "mail")
-	ds := &FileDataStore{path: path, mailPath: mailPath}
-
-	for _, name := range names {
-		mb, err := ds.MailboxFor(name)
-		if err != nil {
-			panic(err)
-		}
-		// Create day old message
-		date := time.Now().Add(-24 * time.Hour)
-		msg := &FileMessage{
-			mailbox: mb.(*FileMailbox),
-			writable: true,
-			Fdate: date,
-			Fid: generatePrefix(date) + "-0000",
-		}
-		msg.Append(testMsg)
-		if err = msg.Close(); err != nil {
-			panic(err)
-		}
-
-		// Create current message
-		date = time.Now()
-		msg = &FileMessage{
-			mailbox: mb.(*FileMailbox),
-			writable: true,
-			Fdate: date,
-			Fid: generatePrefix(date) + "-0000",
-		}
-		msg.Append(testMsg)
-		if err = msg.Close(); err != nil {
-			panic(err)
-		}
-	}
-	return ds
+func (m *MockDataStore) AllMailboxes() ([]Mailbox, error) {
+	args := m.Called()
+	return args.Get(0).([]Mailbox), args.Error(1)
 }
 
-func teardownDataStore(ds *FileDataStore) {
-	if err := os.RemoveAll(ds.path); err != nil {
-		panic(err)
-	}
+// Mock Mailbox object
+type MockMailbox struct {
+	mock.Mock
+}
+
+func (m *MockMailbox) GetMessages() ([]Message, error) {
+	args := m.Called()
+	return args.Get(0).([]Message), args.Error(1)
+}
+
+func (m *MockMailbox) GetMessage(id string) (Message, error) {
+	args := m.Called(id)
+	return args.Get(0).(Message), args.Error(1)
+}
+
+func (m *MockMailbox) NewMessage() Message {
+	args := m.Called()
+	return args.Get(0).(Message)
+}
+
+func (m *MockMailbox) String() string {
+	args := m.Called()
+	return args.String(0)
+}
+
+// Mock Message object
+type MockMessage struct {
+	mock.Mock
+}
+
+func (m *MockMessage) Id() string {
+	args := m.Called()
+	return args.String(0)
+}
+
+func (m *MockMessage) From() string {
+	args := m.Called()
+	return args.String(0)
+}
+
+func (m *MockMessage) Date() time.Time {
+	args := m.Called()
+	return args.Get(0).(time.Time)
+}
+
+func (m *MockMessage) Subject() string {
+	args := m.Called()
+	return args.String(0)
+}
+
+func (m *MockMessage) ReadHeader() (msg *mail.Message, err error) {
+	args := m.Called()
+	return args.Get(0).(*mail.Message), args.Error(1)
+}
+
+func (m *MockMessage) ReadBody() (msg *mail.Message, body *MIMEBody, err error) {
+	args := m.Called()
+	return args.Get(0).(*mail.Message), args.Get(1).(*MIMEBody), args.Error(2)
+}
+
+func (m *MockMessage) ReadRaw() (raw *string, err error) {
+	args := m.Called()
+	return args.Get(0).(*string), args.Error(1)
+}
+
+func (m *MockMessage) Append(data []byte) error {
+	args := m.Called(data)
+	return args.Error(0)
+}
+
+func (m *MockMessage) Close() error {
+	args := m.Called()
+	return args.Error(0)
+}
+
+func (m *MockMessage) Delete() error {
+	args := m.Called()
+	return args.Error(0)
+}
+
+func (m *MockMessage) String() string {
+	args := m.Called()
+	return args.String(0)
 }