Timeout for sending IMAP update

internal/store/change.go

@@ -123,8 +123,16 @@ func (store *Store) imapSendUpdate(update imapBackend.Update) {
 	}
 
 	done := update.Done()
-	go func() { store.imapUpdates <- update }()
+	go func() {
+		// This timeout is to not keep running many blocked goroutines.
+		// In case nothing listens to this channel, this thread should stop.
+		select {
+		case store.imapUpdates <- update:
+		case <-time.After(1 * time.Second):
+		}
+	}()
 
+	// This timeout is to not block IMAP backend by wait for IMAP client.
 	select {
 	case <-done:
 	case <-time.After(1 * time.Second):