PHP Email address validator
Strong Email & Apache Log Analysis with Active Security Features
Sync Outlook with Google, SOGo or any other CalDAV / CardDAV server
Fast Bayesian spam filter along lines suggested by Paul Graham
Anti Spam SMTP Gateway
Zimbra Domain Admin for Zimbra Open Source Edition
one server framework
Multi-protocol server written in Java
An easy-to-use anti-spam email gateway
Win app reads your gmail inbox, autoreplies with jpeg of webcam device
Mail Alert Simple Mailer
Conversion from *.mht files to *.htm files.
cab
Super simple mail merging for Mac OS X using CSV and Mac's Mail.app
Ciphermail email encryption gateway (S/MIME, OpenPGP, PDF encryption)
Synchronizes the Mac OS X Address Book to and from an XML-based format
Python + espeak gmail checker
Liberté Linux: Mission-critical stealth communication
Outlook Headers exposes the Internet Headers of emails.