diff --git a/offlineimap/folder/UIDMaps.py b/offlineimap/folder/UIDMaps.py
index 76c5ee4..5f770ce 100644
--- a/offlineimap/folder/UIDMaps.py
+++ b/offlineimap/folder/UIDMaps.py
@@ -197,6 +197,7 @@ class MappingFolderMixIn:
             self._savemaps(dolock = 0)
         finally:
             self.maplock.release()
+        return uid
 
     def getmessageflags(self, uid):
         return self._mb.getmessageflags(self, self.r2l[uid])