I didn't notice anything in the manual - so apologies if it's covered.

Is there way of preventing a user finally deleting an email? I'd like them to be able to delete a message (at least as far as they think) but the message is actually hidden or moved instead.

It benifits me in that it is easy to restore an accidentally deleted mail very quickly, and also is of use in potential disputes or legal situations where keeping track of mail can be quite important.