I setup his account on my spare mac using outlook and it worked perfectly.
I had him bring me his mac so that I could look at how his account was setup and what version of outlook he was using. Come to find out he was using the online outlook. OWA from office 365.
I have a feeling it was more of a connection issue than an actual issue with his computer or account.
I had him log on and i sent him a few test messages. Both the test computer and his computer received the emails without issue.
thanks for your help on htis.