Adding a Reply-to Line

I need to add a Reply-to line that displays the address of the sender, to
the headers of my mailing list. Apparently the AOL mailer and some of the
Microsoft products can't figure out how to behave if no such line is
present.

Below seems to be the recipe that governs this, but I don't know enough
about this to be sure. This is from rc.submit. Can tell me whether I'm on
the right track?

     #
     # Main header munger for submissions passing through this list.
     #

     oldshellmetas="$SHELLMETAS" SHELLMETAS     # Save a shell, procmail can
                                                # do this one by itself.
     :0 wfh
     | formail -b -IFrom\  -IReceived: -IReturn-Receipt-To: -IErrors-To: \
        -IX-Pmrqc: -IX-Confirm-Reading-To: -IX-Ack: -IAcknowledge-To: \
        -IRead-Receipt-To: -IReturn-Receipt-Requested: -IX-Diagnostic: \
        -iStatus: -iReturn-Path: -iX-Envelope-To: -iX-Envelope-From: \
        -I"Precedence: list" -I"Resent-Sender: $listreq" \
        -uDate: -aMessage-ID: -aResent-Message-ID: \
        -a"To: $listaddr" -a"Resent-From: $listaddr" -A"X-Loop: $listaddr" \
        -a"Subject: Unidentified subject!" ${reply_to:+"-a$reply_to"} \
        -a"X-Mailing-List: <$listaddr> $ARCHIVE"

Thanks,


--Ken
           68 Westy, Admin -- type2 -- The VW Bus Mailing List