Premium Anti-Spam in Ipswitch IMail Secure Server 2006 and Collaboration Suite 2006 Premium, when using a certain .dat file in the StarEngine /data directory from 20060630 or earlier, does not properly receive and implement bullet signature updates, which allows context-dependent attackers to use the server for spam transmission.
http://www.vupen.com/english/advisories/2006/2653
http://securitytracker.com/id?1016420
http://securitytracker.com/id?1016419
http://ipswitch.com/support/imail/releases/security_advisory_20060630.asp
http://ipswitch.com/support/ics/updates/security_advisory_20060630.asp