backup mailman machine

Most of you probably backup up your Mailman machine  and save the
archive on tape or on some other related machine.

What I have attempted to do is create two mailman machines, identical
hardware and software with the same lists on both keeping them in sync.
When one goes down I can use the other, of course both machine have a
different host name, but I use a CNAME (configured in the bind tables)
to keep the same address for users to use their mailing list without
having to switch to a different SMTP Host Name if the primary Mailman
machine goes down. Only problem when I send out messages to the lists,
the To: header field always displays the SMTP host name  not the CNAME
when the message is received. I have tryed using  Masqurading rules in
Red Hat 6.0 Sendmail configuration, but it does not work, which is
below. Has everyone tried this sort of thing, or  does anyone know a
solution to this problem? Why my masquerade  rules will not work?

# Masquerading rules
S1
R$*< <at> mm1.isu.edu>       $ <at>  $1 <  <at>  maillist.isu.edu>
R$*< <at> mm1.isu.edu.>      $ <at>  $1 <  <at>  maillist.isu.edu.>

--
Kory Wheatley              Office Phone 236-3874
Computing & Communication
Academic Computing Analyst sr.

Everything you do must point to him.