`forge`

And then the program assembles and sends the forged message:

        open M, "| $MAIL -f '$opt_f'" 
          or die "Couldn't run $MAIL: $!; aborting";

        print M <<EOM;
        From: $opt_f
        Subject: $subj
        To: $to
        $BCC
        $message
        EOM

        close M 
          or die "Couldn't exec $MAIL: $!; aborting";

        exit 0;