I'm afraid I don't  understand the question. One thing I  can say is that
MAIL-11 +  VMSMAIL is not an  RFC822 mail system, it's  a VMS/DECNET mail
system. It does  not have a *concept* of 'Sender:'  or 'Reply-To:' or the
like, it  knows about the  person who sent  the message, period.  Given a
message with 'From:',  'Sender:' and 'Reply-To:' pointing  to 3 different
addresses, which  one should you select  as the origin (and  recipient of
any reply to the message)?
 
  Eric