Help with setting up incoming mail into the rt helpdesk

I’m having a problem setting up mail incoming to rt
helpdesk (outgoing from it is fine). Its installed on
fedora core 2 and i’ve set up aliases in sendmail.

We have an exchange server that does all our mail for
our maildomain
I’m unsure whether i want rtbox to send mail as (but do i have to set up a full
subdomain and mx records just for this ?) or if i can
do something on ?
I tried adding an mx record for to the
dns used by exchange but i just get it ending up as
deffered. IN MX 5 under the main
domain zone file.
As you can tell i’m confused as to what i need to do
to get external mail to work either going to exchange
and then to the box, or going directly to the box.
Any advice welcome, thanks. I’ve been all thru the
wiki but thats all largely from the on the rtbox point
of view, my mail isn’t routing to the rtbox.

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