Question : 421 4.2.1 unable to connect for some domains

Hey,

New install for migration from exchange 2003 to 2007. I have all mailboxes moved over. I have not yet removed the connections between both servers. I can send and receive mail fine to almost all domains. however some give me the error 451 4.4.0 Primary target ip address responded with: "421 4.2.1 Unable to connect in the queue viewer.
I am able to telnet to most mail servers and get a proper response. one that is not working is to @nb.aibn.com. I am also unable to telnet to their mail server mx.bellaliant.com from the 2007 server. However i can telnet from my DC or old 2003 server no problem.
I have tried disabling the firewall, and a few other items i have seen on other posts but have had no luck.

also there is no edge box. everything is on the one server.

Would love to find out what the heck is up with this. Any ideas are appreciated.

Answer : 421 4.2.1 unable to connect for some domains

i have figured it out.
I have 2 nics on that box. 1 should have been used by default.  the 2nd nic had a gateway to another inet connection. when i was telneting (and even remoted into the server)for some reason it was using the 2nd nic, even though i thought i had set the binding orders for the nic 1 to be primary. not sure why it would not allow to certain mail servers but after i disabled the 2nd nic telnet worked fine and queus cleared out.