Exchange Class Links

Openspf - http://www.openspf.org
IMF manager: http://www.msexchange.org/tutorials/IMF-Managers.html
"The Intelligent Message Filter (IMF) was designed to be a hands-off anti-spam package for Exchange 2003. Compared to other packages there is very little to configure. This means an administrator can set configure a confidence level for blocking mails but none over particular e-mails falsely identified as spam.

However, IMF can store blocked e-mails in an archive directory, which can be browsed and searched. So you can either look at those e-mails yourself or use one of the available third-party free IMF archive managers."