A fake mail server that captures e-mails as files for acceptance testing. This avoids the excessive configuration of setting up a real mail server and trying to extract mail queue content. Sponsered by Wordtracker.
Mstone is a mail performance measurement system. It can simultaneously test SMTP, POP, IMAP, and some HTML based systems. It measures transaction latency in multiple stages, and graphs the combined results from multiple clients.
SMTPA is a penetration testing and email compliance tool. Want to know if a renamed, encrypted MS word document with a wrongly set content-type header fools your Content Security infrastructure? Check this out!
A Bayesian spam filter for SMTP servers, based on Paul Graham's "A Plan for Spam", http://www.paulgraham.com/spam.html. Includes tools for spam-database maintenance & testing config. parameters. Supports sendmail & postfix; others soon. GPL.