IMAP, or LOCAL account using SpamAssassin. It can optionally delete mail
identified as spam or save it to a designated folder, and also can be used
to train a local  SpamAssassin (or a remote one if SpamAssassin >= 3.1 is
installed both locally and remotely). According to your SpamAssassin server
configuration, it can show worse performance than Bogofilter, (slower,
eating more CPU), but can catch spam with better accuracy.

WWW: http://claws-mail.org/plugin.php?plugin=spamassassin