GFI MailSecurity for Exchange/SMTP is an email content checking, exploit detection, threats analysis and anti-virus solution that removes all types of email-borne threats before they can affect an organization’s email users.  

GFI MailSecurity's key features include multiple virus engines, to guarantee higher detection rate and faster response to new viruses; email content and attachment checking, to quarantine dangerous attachments and content; an exploit shield, to protect against present and future viruses based on exploits (e.g., Nimda, Bugbear); an HTML threats engine, to disable HTML scripts; and a Trojan & Executable Scanner, to detect malicious executables.

UPDATE: New notification options have been added to e-mail the recipient or sender when messages are held because of virus, subject line or attachment extension matches. Supports multiple e-mail domains. GroupWise Footnote consists of an easy to install server based NLM that is run alongside the GroupWise Internet Access agent (GWIA). Outgoing signatures or notification messages may be easily changed using NWAdmin32/C1 by editing the GWIA object in NDS.

Some FAQ's and Facts
GWIA Must be running on the server - look for future enhancements in this area
NIMS is not currently supported - sorry, but keep checking
Daily automatic Updates
Multiple Actions for Viruses - Clean, Delete, Ignore, Reject
Multiple Warning Schemes - Sender, Receiver, Admin - Any or All
Use Regular Expressions for Content Filtering.
RAV is an NLM that will scan files upon open, close and write in real time.
RAV for GroupWise is an NLM that scans email for viruses in real time.