I'd use opensmtpd instead of postfix. Mostly because you'll learn how to configure the former in a matter of tens of minutes when reading the man page, and the config format is basically English.
The latter. Not even close.
I second this. Setup roundcube and postfix in about a day on a remote server, and now for $5 a month I have control over my email (make sure encryption is enabled when communicating with it, obviously).