1)   SPAMfighter Exchange Module 3.5.5.0
SPAMfighter Exchange module is the easy-to-use anti-spam/virus solution for Microsoft Exchange Server 2000/2003/2007/2010 and Microsoft SBS. English, German, Danish, Dutch, Spanish, French, Greek, Swedish, Japanese, Norwegian, Czech, Polish

 2)   mxORB 2.2.3
mxORB is a server-side spam filter that consistently blocks over 98% of unsolicited commercial email (also known as spam) at a fraction of the cost of other filtering solutions.

 3)   SecurityGateway for Exchange / SMTP 2.0.3
SecurityGateway email spam firewall for Exchange/SMTP Servers protects against viruses, phishing, spoofing, and other malware. Analyze, manage, and report on email traffic patterns. Simple Administration, Powerful Filtering, Accurate Results!

 4)   PostGuard Spam Filter 3.5
Sentinare PostGuard - Secure encrypted spam and virus free email for your home or business. 99% accurate filtering solution includes 1GB of email storage that will never be subjected to email marketing or advertisements. Your privacy, our priority.