🚀 go-pugleaf

 >    Also, if it didn't prompt in the minibuffer, but rather gave you a
 >    sendmail-type buffer, those of us who store our mail aliases in
 >    mail-mode word-abbrevs would have a fighting chance.
 > 
 > Yes!  Yes!  Yes!
 > 
 > At least have this as an option.  Simply prepare a mail buffer with the
 > necessary `resent' headers.

Why not just type your comment in at the top of the message, in
brackets or something.  The comments would be more likely to be
seen by users who have mailers that don't show alien headers.
God knows I've gotten enough complains about forwarded messages
having too many furshlugginer headers... :->