1)   602LAN SUITE 6.0.08.0916
Secure messaging solution with web collaboration containing SMTP/IMAP/POP3/LDAP services along with integrated anti-virus and advanced anti-spam protection. Native Outlook support provides synchronization of mail, contacts, tasks, and calendar items.

 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)   SpamSquash 2.0.1
SpamSquash is a spam filter that uses two methods for filtering, a Bayesian filter and DNS black lists. It's used with a third party pop3 email client, such as MS Outlook and Pegasus Mail. It also includes white and black lists. Gets over 99%.

 4)   ORF Enterprise Edition 2.1
ORF Enterprise Edition is an enterprise-level anti-spam solution that helps you to block spam before it reaches your network. ORF uses a combination of anti-spam technologies to stop the spam on SMTP protocol level.

 5)   Anti-Spam Blacklist Thing 1.1
Anti-Spam Blacklist Thing lets you check to see if a given IP address or hostname is on one of up to 20 different anti-spam blacklists. Anti-Spam Blacklist Thing is provided by SpamButcher completely free of charge.