I recently had two of my post deleted by a forum moderator, and I've been pondering on what grounds he/she might have done that.

I think now, the reason for deleting a post should come along with the notification.
And the user should be made aware of the rules he/she is supposedly breaking.

And admins, if possible could flag a post and message the user to delete it himself. Not this anonymous process, where you have no idea which moderator deleted your post.