[Extracted from Blair Dillaway's mail to the list.]

-          Given the behaviors are based on the presence of message forwarding intermediaries, you really need to be 
precise in defining this. I expect you mean the case where the sender is transmitting a message to an end-point which it
 knows is not the ultimate recipient for the message body. I suspect you don’t consider a transparent firewall or 
router to be an intermediary.