dovecot-antispam : A dovecot antispam plugin supporting multiple backends ( http://wiki2.dovecot.org/Plugins/Antispam/ )
dovecot-antispam-sieve : Integrates spam learning into Dovecot by Sieve ( https://wiki.dovecot.org/HowTo/AntispamWithSieve )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a hering-overlay
For Paludis use this rsync : rsync://gentoo.zugaina.org/hering-overlay-portage
If you have a problem : ycarus(-at-)zugaina.org