Exchange 2003 Intelligent Message Filter
I've been playing with the Intelligent Message Filter trying to get it to bypass certain messages. There are 2 ways of doing this:
Use SMTP authentication. Authenticated messages like those also submitted by MAPI clients to Exchange won't be processed by the IMF. You could also
add the sender's SMTP server's IP address to the Allow Address exception override in Connection Filtering. IP Allow addresses under connection filtering will bypass the Intelligent Mail Filter and result in messages that have no Spam Confidence Level (SCL) value stamped. The IMF release notes can be found here, and there is also a Deployment guide available.