Free l.a.u.r.a software for linux

L.A.U.R.A project provides a secure and performant e-mail proxy designed with the goal of shutting down the "Unsolicited Commercial/Bulk E-mail Era".
What is "Greenmarking"?
Greenmarking is something I think I invented myself (I might be wrong though, I coulndt find it anywhere else). Greenmarking works like this: if a triplet of (sender_ip, sender, recipient) is first seen, it gets marked green. The message will be sent unmarked with the meaning of "never seen it before". Next time the triplet is met, the message will also be marked green, meaning "I know this guy already".
Yes I know this sounds like greylisting (its a variation of it, hence the name). However, greenmarking is (and should be) done after greylisting. Why? Greylisting mostly means that the passing message is almost certalny originating from a valid (E)SMTP mail server daemon. Worms usually dont retry too much. So greenmarking is effective especially against evil mail selvers. Its implemented in the project. Just add an Inbox filter to your (web)mail client and move all the messages with a "neverseen" header in a special suspect folder. If you dont want to hassle with them, activate the Inbox filter only after youve run the greenmarking daemon for a while (1/2 weeks maybe?).
Main features:
- ESMTP capability for interoperating with Postfix
- Lightening fast B+ infrastructure for internal database
- No false positives
- No "lost" e-mail messages
- No miss-rate
- BSD license (the most liberal and FREE, in honour to the FreeBSD team)
- Its written in plain old C
- It was designed to be as fast as applicable
- It is (going to be) very secure (multiple audits, formal verifications, programming care)
- No package dependencies - no extra libraries or tools needed
- Hassle-free for admins - just install it
- Hassle-free for users - it just works, without user intervention
- Hassle-free and polite with other Internet neighbours - no rude messages, nothing
- Secure inter-server cooperation for MX backups - without any hassle or complexity (needs to be done)