I host my own mail server here at Foobar Labs. Why? Mainly because I'm not a huge fan of the ISP or commercial alternatives. Anyway, my main mail server/workstation died a few months ago due to a bad power supply. It did the spam scanning of incoming email using MailScanner (good stuff, and free). Mail was stored on an isci share from FreeNas and picked up by Dovecot IMAP/POP3 software. My RPi (a 2B+) was sitting on the bench unused and had a wild idea. Why not try and use it for my mail server until the new power supply came in? I took the my backed up config files from the dead box and put them on the Pi with minimal editing, loaded up postfix and dovecot, then got the MailScanner installer from MailScanner.org which scans for both spam and malware. I mounted the iscsi share and fired everything up. It was pretty slow when scanning incoming mail, but it worked! These little guys are considerably more powerful than I'd believed. Post your stupid RPi tricks.