Anti-Spam SMTP Proxy Server implements multiple spam filters
Universal server
Fast Bayesian spam filter along lines suggested by Paul Graham
Anti Spam SMTP Gateway
Booking/reservation of meeting rooms/equipment with e-mail invitations
Script set to archive emails at groupwise server side
Zentyal is a Linux Small Business Server
Full SMTP/Mail server Appliance in 5 minutes
Open Source Anti-Spam and Anti-Virus Gateway
Virtual Appliance of RadicalSpam
AV/content filter for Qmail
A simple archive system for emails