[copy&paste from https://bugs.kde.org/show_bug.cgi?id=294517 ] When moving (by drag & drop) emails from a folder (say 'inbox') to another (say 'filtered'), the emails are moved, but marked as unread in the new location, before after a few seconds they reappear, duplicated, in the original folder and marked as unread as well (even if they were marked as read before). The emails are all local, no remote server involved. Emails were fetched from a POP3 account before. [end copy&paste] In my case, I moved the mails from a local folder to a folder in an IMAP account, and they re-appeared in the local folder. Note: This doesn't happen always. Moving _lots of mails_ (select 30 mails, move them at once) makes this more likely to happen.
Sorry, this bugreport was accidently submitted twice, see bug 374738 for it's (still open, and valid) twin.