Hi, all!

I have 8 POP3 accounts managed by KMail. Mails are downloaded and distributed to ca. 100 subfolders of the inbox according to filter in KMail.
Since upgrade to 42.1 regularly comes up a problem of "buggy" mail, that gets stuck in the inbox and is not getting moved to the destination folder, but merely copied.
Such a mail is not visible in the inbox, but its copies overfill the destination folder, being copied every time I click the inbox. This mess can be ended only by deleting the responsible filter. The "buggy" mail appears in the inbox and can be deleted. But the copies cannot be deleted! After each try comes the message "Retrieving folder contents" and KMail hangs up.

So the question is: how can I deleted such mail copies?

This has only been (partially, at least) fixed in more recent versions of KMail. I take you mention openSUSE Leap 42.1: it won't get this update due to having reached its end of life support period.
As far as I understand, only Leap 42.3 incorporates this fix.