Package request: dovecot-antispam-plugin
The antispam plugin allows you to retrain the spam filter by simply moving emails in and out of the Spam folder.
Main URL: http://wiki2.dovecot.org/Plugins/Antispam
Src: hg clone http://hg.dovecot.org/dovecot-antispam-plugin
(from redmine: issue id 2602, created on 2014-01-15, closed on 2015-12-17)