[Mailman-Users] masquerading

Greetings! I am searching for an appropriate question to ask concerning
sendmail host masquerading, however, I first need some information.
When I send a message to two different hostnames which point to the same
sendmail server, I would like mailman to resend out that mail with the
hostname which the mail was sent under. Example:
sub1.domain.com and sub2.domain.com point to smtp.domain.com
mail is sent to newlist1 at sub1.* and it is resent out with smtp.*
mail is sent to newlist2 at sub2.* and it is resent out with smtp.*
Both From: and Reply-to: are set to smtp instead of the sub1 or sub2
What I want:
mail is sent to newlist1 at sub1.* and it is resent out with sub1.*
mail is sent to newlist2 at sub2.* and it is resent out with sub2.*

I thought the host_name (general) setting would accomplish this, but no
matter what I put in there, the sendmail server sends the mail out with
the machine's hostname. I looked for DM in sendmail.cf and it is null.
Is there something else I should be looking at? What should I be asking
here? I would appreciate any insight which would help me form an
appropriate question to ask sendmail folks or better yet, a solution to
my problem.

Cheers!