Occasionally I have a user claiming that some of their email is missing (in Exchange 2003 and now even in 2007). The person will report that they looked at it in outlookweb and then go to their outlook client and the message will be gone. I know Exchange has message tracking logs for recording the incoming/outgoing emails while in transit, but is there any kind of logs that supplies information as to what actually happens to a message? Like if a user deletes a message or moves it to a different folder? I am at a loss here so if anyone could give me pointers on how to deal with these types of users I would be grateful.

check the users outlook rules...probably something funky, if its in owa, then not outlook, its a client issue for sure. If nothing else, put some spyware on the machine and watch em.