I had to delete a users AD & Exchange account. I recreated it with the exact same email address. The user now can't receive internal email from the company but is email from external account. I deleted the auto complete option from my outlook client, tried to send from the GAL and it failed. He did receive the email if I sent it from OWA, and from my gmail account. The image below is the bounce back message. Any help will be appreciated.
I'm running exchange 2010 on server 2k8. He's outlook client is 2010.