Mail Server Problem

So I set up my server and I pretty much running every service and using it. I have NAT setup and I have internal DNS domain.lan pointing to my 192.xx.xx.xx NIC1. Then I have my external DNS pointing to domain.com 64.xx.xx.xx NIC2.

Everything is working great! EXCEPT mail. My web is working and it is resolving outside so I know it works. DNS seems to be setup fine I can do a dig from the outside and inside and it looks good. I can also do a dig mx and that looks fine as well.

But when I go to check mail it says the server can not be found and same with sending. Webmail seems to work for sending but it does not receive mail.

Does it not like having NAT, internal DNS, and external on the same box? (Firewall is not the problem, the proper ports are open) I would love to get this working, any of you have ideas?

Thanks