I have an interesting twist for you that proves this is a Cox problem caused by their "upgraded" system. I have both Cox Business and Residential internet service. Initially, I had two business services, but I downgraded my one at home to Residential when I no longer needed a static IP there, but as a result, I have several legacy email accounts that are occoxmail.com and I have one new cox.net account. My legacy accounts work fine no matter which connection I am on and my cox.net account will not connect at either location. My non-Cox email also works fine. Therefore, this is clearly a Cox Mail Server problem and not Outlook, server addresses or anything else. I plan to close my one cox.net account and replace it with some gmail or yahoo acct.