This applies to kmail, verified when running in Kontact 5.3.0 Procedure followed: Take an existing folder from kmail and drag it into the field "preferred" (folder view). Create a filter for the mail to be put into that folder. Now, with the filter working well, take this action on the original folder: change the name in properties to a new name. In my case, a mixed name, Latin and Chinese character. The folder name in the main list will update correctly. The filters will update also correctly. But the preferred list will show the original name. Interestingly the popup when hovering over that preferred folder shows the new name. Also properties shows the normal name. But now way to make that name appear in the preferred list. When trying to drag the folder with the correct (new) name into the preferred list, nothing happens (as expected because the folder is there). Dragging in of other folder works normally. The name of the folder hit by the problem does however not update. Finally I tried the following. Go into rename preferred folder and click on the button rename preferred. Then this works. For me this is a bug, because the behaviour should be to update everything included the preferred list, provided that properties of the folder are updated and filters also. The function "rename preferred" should work instead "other way round" as if one wants to rename on purpose the folder, he should be able to do it. But the current status is not intuitive. Reported originally against Leap 42.2 as Bug 1046908 https://bugzilla.opensuse.org/show_bug.cgi?id=1046908 by request.
it works here. 5.3.0 is very old we will release 5.7.0 in 2 weeks. could you retest on new version thanks. Reopen it if you still have this bug.