Outlook won't send, have tried everything.

I have one user that can't send email using Outlook '03 or '07. He can receive fine, just no send. There are no sending limits imposed on his account through Exchange 2003. He connects using Outlook Client running OWA in the background as a proxy(I know it is clunky as hell, but thankfully I didn't set it up or am I allowed to change it). Anyway, if he connects directly to OWA through IE he can send no problem. I have tried new profiles with 2 different user accounts. All with the same result of no send. The other two users in his office have no problems. I have even sent him a new laptop. The problem seems to be occurring when he is in his office, he said it works fine from home.