Cox e-mail not working correctly

A friend sent me an e-mail about an hour ago.  When I went to retrieve it, it wasn't on my Mail (Safari ver 10.1.1).  I then tried "Get New E-mail" and there was some kind of problem. it said "Cox not responding, check settings".  I shut down Mail and reopened it - as this sometimes works. It then said it was downloading 5 messages, but only downloaded 1.  So I went to Cox.net and tried to see what was on the server, only the single message was on there too, and it took forever to load.  I also checked "Spam" and "@SaneLater"  No other messages were on those either.

Cox has been pretty unreliable since January.  What is going on?