[GODT-797] EXPUNGE waits for APPEND to prevent data loss when Outlook moves from Spam to Inbox

internal/imap/mailbox_message.go

@@ -70,6 +70,9 @@ func (im *imapMailbox) CreateMessage(flags []string, date time.Time, body imap.L
 	// Called from go-imap in goroutines - we need to handle panics for each function.
 	defer im.panicHandler.HandlePanic()
 
+	im.user.appendStarted()
+	defer im.user.appendFinished()
+
 	m, _, _, readers, err := message.Parse(body)
 	if err != nil {
 		return err