Only send directory info once from maildir

The directory info only needs to be sent once for all the messages, this
reduces unnecessary messages being sent which could lock up the ui.

worker/maildir/worker.go

@@ -498,11 +498,12 @@ func (w *Worker) handleFlagMessages(msg *types.FlagMessages) error {
 			Message: types.RespondTo(msg),
 			Info:    info,
 		}, nil)
+	}
 
 	w.worker.PostMessage(&types.DirectoryInfo{
 		Info: w.getDirectoryInfo(w.selectedName),
 	}, nil)
-	}
+
 	return nil
 }