unless the sender or the receive asks for it to be posted in a specific scam accusation thread.
That creates the same problem: I can't know who the receiver is if they were in a BCC. And even if there are 2 known receivers already, there could always be a third in BCC.
There is a way to solve this but not sure if it's worth the hassle! You can hide PM ids on the PM_publisher/ page. Anyone who sends a
publish request has to provide the the
sender username and the correct
PM_id as arguments. If they match then he is indeed a BCC recipient. You'll have to limit the number of requests a user can send (i.e 5 per day) to prevent him from trying to guess the correct id.
This suggestion is regarding the publish feature not the destruct suggested by mocacinno