Sometimes, but not always, mail filtering does not work at all with recent versions of kmail and akonadi-server, at least with akonadi-server-1.11.0 and kmail-4.12.2. When I boot my machine and kmail starts automatically, most of the time, no filtering is done at all and all emails go to the inbox (which is really annoying as I use a lot of filters and have to put them into their destination folders by hand).

The mail filter protocol is simply empty. Nothing is done. I don't know if this only affects POP3 accounts – at least, I only use POP3.

Sometimes, closing kmail, logging out of KDE, restarting kdm, logging back in and restarting kmail helps and filtering starts working again.

I really don't know how to debug this. No error message is displayed, no log file written. It simply doesn't work and sometimes starts to work again for a reason I don't know.

I had the same behavior with kmail-4.12.1, but with 4.12.2, it happens much more often.

This is really annoying. I'd really like to help to track this down if someone would tell me HOW I can find out why this happens.

Reproducible: Sometimes