The title of this post should be "Spam Filtering on OpenSMTPD", but i didn't want to define the my home page with that word. Running an e-mail server is a challanging and low-reward task, so we need to keep this as simple as we possibly can. This is I classify mail using SpamAssasin these days.
Sagator is an email antivirus/antispam gateway. It is an interface to the postfix, sendmail, or any other smtpd, which runs antivirus and/or spamchecker. It's modular architecture can use any combination of antivirus/spamchecker according to configuration.