diff --git a/smtpd/listener.go b/smtpd/listener.go
index fe4286d..e7faffd 100644
--- a/smtpd/listener.go
+++ b/smtpd/listener.go
@@ -101,7 +101,7 @@ func (s *Server) Start() {
 	}
 
 	// Start retention scanner
-	StartRetentionScanner(s.dataStore)
+	StartRetentionScanner(s.dataStore, s.globalShutdown)
 
 	// Listener go routine
 	go s.serve()
@@ -177,6 +177,7 @@ func (s *Server) Drain() {
 	// Wait for sessions to close
 	s.waitgroup.Wait()
 	log.Tracef("SMTP connections have drained")
+	RetentionJoin()
 }
 
 // When the provided Ticker ticks, we update our metrics history
diff --git a/smtpd/retention.go b/smtpd/retention.go
index ac1b3f8..ea3642c 100644
--- a/smtpd/retention.go
+++ b/smtpd/retention.go
@@ -10,24 +10,34 @@ import (
 	"github.com/jhillyerd/inbucket/log"
 )
 
-var retentionScanCompleted time.Time
-var retentionScanCompletedMu sync.RWMutex
+var (
+	retentionScanCompleted   = time.Now()
+	retentionScanCompletedMu sync.RWMutex
 
-var expRetentionDeletesTotal = new(expvar.Int)
-var expRetentionPeriod = new(expvar.Int)
-var expRetainedCurrent = new(expvar.Int)
+	// Indicates Inbucket needs to shut down
+	globalShutdown chan bool
+	// Indicates the retention scanner has shut down
+	retentionShutdown chan bool
 
-// History of certain stats
-var retentionDeletesHist = list.New()
-var retainedHist = list.New()
+	// History counters
+	expRetentionDeletesTotal = new(expvar.Int)
+	expRetentionPeriod       = new(expvar.Int)
+	expRetainedCurrent       = new(expvar.Int)
 
-// History rendered as comma delimited string
-var expRetentionDeletesHist = new(expvar.String)
-var expRetainedHist = new(expvar.String)
+	// History of certain stats
+	retentionDeletesHist = list.New()
+	retainedHist         = list.New()
+
+	// History rendered as comma delimited string
+	expRetentionDeletesHist = new(expvar.String)
+	expRetainedHist         = new(expvar.String)
+)
 
 // StartRetentionScanner launches a go-routine that scans for expired
 // messages, following the configured interval
-func StartRetentionScanner(ds DataStore) {
+func StartRetentionScanner(ds DataStore, shutdownChannel chan bool) {
+	globalShutdown = shutdownChannel
+	retentionShutdown = make(chan bool)
 	cfg := config.GetDataStoreConfig()
 	expRetentionPeriod.Set(int64(cfg.RetentionMinutes * 60))
 	if cfg.RetentionMinutes > 0 {
@@ -37,26 +47,42 @@ func StartRetentionScanner(ds DataStore) {
 			time.Duration(cfg.RetentionSleep)*time.Millisecond)
 	} else {
 		log.Infof("Retention scanner disabled")
+		close(retentionShutdown)
 	}
 }
 
 func retentionScanner(ds DataStore, maxAge time.Duration, sleep time.Duration) {
 	start := time.Now()
+retentionLoop:
 	for {
 		// Prevent scanner from running more than once a minute
 		since := time.Since(start)
 		if since < time.Minute {
 			dur := time.Minute - since
 			log.Tracef("Retention scanner sleeping for %v", dur)
-			time.Sleep(dur)
+			select {
+			case _ = <-globalShutdown:
+				break retentionLoop
+			case _ = <-time.After(dur):
+			}
 		}
-		start = time.Now()
 
 		// Kickoff scan
+		start = time.Now()
 		if err := doRetentionScan(ds, maxAge, sleep); err != nil {
 			log.Errorf("Error during retention scan: %v", err)
 		}
+
+		// Check for global shutdown
+		select {
+		case _ = <-globalShutdown:
+			break retentionLoop
+		default:
+		}
 	}
+
+	log.Tracef("Retention scanner shut down")
+	close(retentionShutdown)
 }
 
 // doRetentionScan does a single pass of all mailboxes looking for messages that can be purged
@@ -88,6 +114,13 @@ func doRetentionScan(ds DataStore, maxAge time.Duration, sleep time.Duration) er
 				retained++
 			}
 		}
+		// Check for shutdown
+		select {
+		case _ = <-globalShutdown:
+			log.Tracef("Retention scan aborted due to shutdown")
+			return nil
+		default:
+		}
 		// Sleep after completing a mailbox
 		time.Sleep(sleep)
 	}
@@ -98,6 +131,13 @@ func doRetentionScan(ds DataStore, maxAge time.Duration, sleep time.Duration) er
 	return nil
 }
 
+// RetentionJoin does not retun until the retention scanner has shut down
+func RetentionJoin() {
+	select {
+	case _ = <-retentionShutdown:
+	}
+}
+
 func setRetentionScanCompleted(t time.Time) {
 	retentionScanCompletedMu.Lock()
 	defer retentionScanCompletedMu.Unlock()