2018 -7/29 - Webmail - Cox is blocking my outgoing (not incoming) Outlook emails as spam for last several days

 I was having the exact same problem for a long time.  I checked and double checked my settings.  The solution for Outlook is when you are entering the last set of port numbers, for outgoing server it is 465,  you MUST move off that box. Click anywhere, I clicked on the box about leaving mail on server.  Anyway the point is that until you move off that port number box the port remains open ended and thus the server can not be reached.  Try my suggestion and see if it works for you.