One Sticky Point

We have an exchange server running but it does not do lists nearly as
well as Majordomo.  So I installed linux / majordomo / postfix on a box
and got them working.  Here is what I do not know.  Is it possible to
have the linux server running in the same domain as the exchange?  I
can't figure out how emails would ever arrive at the linux box with
exchange as the primary mx.  So if I am right on that, I believe I may
need to setup another domain like <lists.mydomain.com> and make the
majordomo server the primary mx for that domain then send emails to
[email protected].
 
Is my thought process correct here?