fdm is a simple, lightweight replacement for mail fetch, filter and delivery programs such as fetchmail and procmail. It can fetch using POP3 or IMAP (with SSL) or from stdin, and deliver to a pipe, file, maildir, mbox or SMTP server, based on regexp
I am using fdm in my new FreeBSD email server. Simple to integrate with Dovecot and Postfix. For simple email filtering the fdm syntax is better than sieve, IMHO.
This is exactly what I've been looking for. fdm and it's config syntax are really good.