I have an @Cox.net email account. Yahoo took over management of the Cox servers about a year ago. I use the Outlook client for email on my Windows PC and on my Android phone. There has been a recent udate to the Android program that required me to reauthenticate my password. When I did it gave me an error. Yahoo support didn't know how to fix the issue.

I finally figured out that I had to delete the old account and set it up again. However, this time I used 'myname'@yahoo.com as my email address. That took me to the Yahoo login and authorization page. Once there, I was able to change my email address to my @cox.net email and I was able to regain access to all my emails.