It was inevitable. I believe the Mail.app mail client that we all love has been exploited. (Or, given the benefit of the doubt, this could be an obscure bug of some kind, or related to some other compromise somewhere else in the system - i.e. I'm not promising my machine hasn't been compromised in some other fashion with some changes made to the Mail.app).
Symptom
A email arrives in my inbox. Mail.app recognizes that the email is junk. The email is moved to my Junk folder. The Junk Folder displays the number "1" indicating that there is an email in the Junk Folder. When I click on the Junk folder to view the email, the email deletes itself. If the email can delete itself, who knows what else it can do.
I've noticed this behavior twice in the last week. Today, I'm trying to track it down. My guess is that it is a GIF or other image related exploit since Mail.app automatically displays inline GIFs (and there are no preferences to prevent this ).
