Third comment, but it bears repeating. Dovecot. I use it with Postfix, using Dovecot's virtual domain support to host various domains/mailboxes. Dovecot with s

Third comment, but it bears repeating. Dovecot. I use it with Postfix, using Dovecot's virtual domain support to host various domains/mailboxes. Dovecot with sieve sorts mail server side. It's fast and works incredibly well.