My favorite SMTP server is Postfix. I’ve been using it for over five years and its never let me down. I’ve used it on Gentoo and Debian, and still do today.
I setup the following features:
- UCE Controls
- SASL Authentication
- Virtual domains and mailboxes
- Maildrop transport for Spamsasssin integration
- Backup MX servers as relays
All in all, its awesome!