I am having the exact same problem suddenly. We're running EX2k7 and windows 2003, but the situation is the same. The message gets delivered to the user's mailbox and is then IMMEDIATELY deleted. If I click Tools, Recover Deleted items, we can see all 12 of the e-mails that came from rim and were delivered and then immediately deleted. Same thing, no server rules, nothing in the environment has changed... I had a problem with this some time ago, only it was with messages from our copier, and I can't remember what I did to fix it. I want to say it was MS's junk filter doing it but I tried that with no luck as well.