LISTSERV 16.0 - MSUNAG Archives

I have an MSU DSL connection, hence a 35.11.x.x IP address. Sometime within the last few days, Outlook in corporate mode has stopped working for me. I get prompted for a password, and then after a l-o-n-g pause, I'm told my Exchange Server is unavailable. I'm then prompted to work offline, retry or cancel. I've checked with Health Team IS (who manage the Exchange Server) and am told that they have changed nothing recently, and that the server is working fine. What's the status of campus port blocking? Any idea why I can no longer use Outlook in corporate mode? I have users complaining about this too.