As for functionality, Maildir with your MDA of choice gives you all kinds of rube-goldberg opportunities with text files. No silly "max connections" junk when

As for functionality, Maildir with your MDA of choice gives you all kinds of rube-goldberg opportunities with text files. No silly "max connections" junk when your phone and your laptop hit IMAP at the same time. The one thing I really liked when going from procmail/postfix/dovecot to Google Apps was spam filtering. I hated keeping up to date with the various new methods spammers discovered to offer me good times with farm animals. Today, I get a lot of false positives, especially with the "this is spam because other people marked messages like this as spam" emails from my bank. I miss emails from family members, travel vendors, and even online shipment confirmation messages. I've had to create rules to catch them and move them to folders/labels as well as have a client-side process occasionally search for a whitelist and "rescue" the messages.