Virtual Qmail - virtual domains management system for qmail. It is designed to be fast, reliable, and easy to use. Includes software allowing users to manage their accounts via WWW.
mailgate is a set of Python scripts we used at my former company to transfer email a) from a POP3 account to our internal mail server, b) from a POP3 account to a mailbox file and c) from a mailbox file to a SMTP server.