I just finished delivering a webcast on Implementing Exchange Server 2003 Security.  If you want to view this later, please visit this link.

During the webcast, I did a demo on Block List configuration, but used some "dummy" RBL providers.  I said I would list some of the providers that I've had good success with in the past and here they are:

www.spamhaus.org
www.sorbs.net
www.ordb.org

Keep in mind, this does not mean Microsoft recommends these or has any association or preference of one over another.

During my webcast, I also mentioned a few registry entries associated with the Exchange Intelligent Message Filter and wanted to post them here for you reference:

For all of the settings, the Registry Key is: HKey_Local_Machine\Software\Microsoft\Exchange\ContentFilter

   Set Archive Director: STRING Name: ArchiveDir = [full path to directory]
   Store SCL with Archived Message: DWORD Name: ArchiveSCL = 1
   Filter Messages through Authenticated Connections: DWORD Name: CheckAuthSessions = 1

Since this is a filter technology, we will (and do) have periodic updates for the IMF so please check on a regular basis for these updates.

If you choose to install an AntiVirus program that does realtime file scanning on your Exchange Server, please omit all the directories that Exchange uses to store messages as well as Dabatases.  If you don't do this, you increase the chances for the AntiVirus program to corrupt your Exchange Database - this is a BAD thing.

Thanks!