Anti-Spam SMTP Proxy Server implements multiple spam filters
IGSuite is a web-ajax-based Integrated Groupware Suite
Booking/reservation of meeting rooms/equipment with e-mail invitations
Unified Communications Server
command line tool to manage email (alias-)domains/accounts/aliases …
JavaScript/XML engine for Apache
An easy-to-use anti-spam email gateway
Jnestor is another majordomo in java
an 'auto-reply' bot for your mail server