We use hosted Exchange 2010.
I have one Mac Outlook user with this problem which has occurred three times in the past 7 months.
The inbox folder gets entirely deleted and the email goes straight to "permanently deleted". He's never seen this occur while using outlook..he simply opens his email and the inbox is empty with everything dumped to permanently deleted.
He swears he is not doing this manually and is not being prompted by any "are you sure that you want to permanently the selected item(s)?"
There are no client-side rules that would cause this.
This is happening only to him out of about 100 users on the same hosted exchange. It is likely some action he is taking but we cannot reproduce it. He is less than "software savvy". I am able to restore from backup but this is a very time-intensive task and not something he or I can sustain as standard operating procedure.