When replying to a message no additional "Re:" label should be inserted before the subject if such a translated label is found. The client therefore should know the commonly used / translated versions of "Re:" preferably editable via preferences.
i.e. In Dutch Betr: is used and in ...
it would be handy to add another way of indexing bookmarks, for example via labels.
this is done for exampel with Google Bookmarks (see image)