Ask HN: Hacking Mail Server

Whats the best way to setup and configure a mail server for your application so that you may parse incoming messages and perform some functionality accordingly.

For instance I have an application in Python/Django for sending free SMS to your friends in Pakistan. I wanna add mail capabilities in it so that every registered user gets an email address like <phone>@isms.pk and any mail sent on it is processed and sent through my SMS gateway. Surely, I wouldn't want a "Mailbox" for each user and periodically check all the mailboxes using IMAP/POP3. Some hacking of MailServer to put some hooks would be a much better idea.

I'm on Ubuntu Linux and my preferred language is Python. Which mail server is the best choice in such scenarios?