stuck on a mail issue

I am setting up a leopard server from fresh install and updated to 10.5.2
I have set up the DNS with godaddy and the reverse with comcast and the changeip -checkhostname comes back good.

I have the mail domain set to a different domain (otherdomain.com) than the FQDN of the server (for testing purposes before we switch current mail server from godaddy to the xserve)

i.e. server = xserve.domain.com, mail domain = otherdomain.com, pop server = mail.otherdomain.com, smtp server = xserve.domain.com

I have DNS settings for otherdomain.com set correctly. (at least according to godaddy)

All users are setup in Open Dir and working correctly.

I can send and receive mail from inside the domain (bob@otherdomain.com sends and receives from frank@otherdomain.com)
I can send mail to outside addresses (bob@otherdomain.com successfully sends mail to sally@comcast.net)
But I cannot receive mail from outside the domain (mail from sally@comcast.net never makes it to bob@otherdomain.com). Sally gets a “Delivery to the following recipient has been delayed:” message.

I hope I gave enough info. If not please let me know what else you need to know.

Thanks

-Justin