Ubuntu + Postfix + Courier IMAP + MySQL + Amavisd-new + SpamAssassin + ClamAV + SASL + TLS + SquirrelMail + Postgrey, pretty cool.

As we are on it, that greylisting policy thing is really annoying to me. The idea is that " All it does is on first contact for specific from-to combinations, tells the sender server to try again in a little while, which most spammers cant afford to do. When proper servers try again after a few minutes it lets it through. " But why do I start to receive emails that were sent a week ago? Either the policy sucks, or the admins suck. Also see the announcement made by the admins: Greylisting is a measure designed to reduce the level of spam being handled by our mailserver (MTA) by temporarily rejecting incoming mail and waiting for a resend attempt by the originating MTA. Legitimate and RFC compliant servers will re-attempt delivery after some interval, generally 1-4 hours later; spammers do not. After our server has "seen" a 'tuple' of sender, recipient and server IP addresses inside a certain time interval, it recognizes a second connection as a reattempt and accepts the mail. The tuple is then added to the whitelist and any mail matching it is automatically relayed. For more information see the greylisting whitepaper or visit greylisting.org. In contrast, the university service is more user friendly.