Postfix Enabler helps Mac users set up a totally-functional buzzword-compliant mail server in less than a minute, the Mac Way. It sets up SMTP, POP3 and IMAP services, with or without SSL support. It even sets up SSL test certs so that you can test the SSL connection. It enables SASL Authentication so you can connect to ISPs who require the SMTP connection to be authenticated. Or, the other way around, it allows you to turn on SMTP-AUTH on the server, so that you can authorise remote users who need to send mail through it.
Plus, it has a few other features, including the ability to set up a roving SMTP server for PowerBook users to send mail wherever they are, whenever they want, so long as they have an Internet connection.