My work domain: bluebirdnetwork.com
External domain: bbn.us.com
External mail server: mx1.bbn.us.com
Local Mail server: mail1.bluebirdnetwork.local is a member of the bluebirdnetwork.com domain but sends mail for bbn.us.com
Our hosted email: Office 365
I can't get mail from bbn.us.com to bluebirdnetwork.com. I can send and receive to/from every other domain. I can send from bluebirdnetwork.com TO bbn.us.com. I can even send to bluebirdnetwork.onmicrosoft.com. Only mail coming from bbn.us.com and going to bluebirdnetwork.com is failing. Any ideas? Internal DNS issues maybe?