Ok Michael, now please  explain me how the Multics mailer  will react when I
place an "Errors-To: CCMRG@BOSTONU" in the mail header.
 
  The Multics mailer is obviously the culprit. It is generating a new piece of
mail with a different message-id, telling you that your original piece of mail
(which one?) has been processed without crashing the Multics system (hey, good
news!!). It's more  or less the same as  a DVM which would be  subscribed to a
list and  would send out a  piece of mail  saying "Buuurps" to the  list every
time a contribution is received.
 
  Eric