Once I received the email from Cox telling me it was now time for me to transition to Yahoo Mail (around March 14, 2024), I used the IMAP settings at https://help.yahoo.com/kb/devices-sln3697.html. I immediately transitioned and it has worked perfectly since March 14th. I can now send and receive my cox.net email using the Outlook email client (both traditional and "new" Outlook). The key to successfully setting your Cox.net email up in Yahoo Mail lies in whether your Cox.net data has been MIGRATED to Yahoo Mail yet. If it has not, you can try to set up the email client you're using all day long and you WILL NOT successfully log in to the Yahoo Mail servers. Yahoo Mail has to be able to recognize your Cox.net email address and can only do so once Cox has migrated your data to Yahoo mail.
I think this is the best advice for people who are having problems with the transitioning. The key is your data from Cox has to be transitioned over to Yahoo first before any of the account setting changes using Yahoo's server domain and port settings will work. For us, so far we have only received the "Almost time... " emails.
I would drop Cox like a bad habit and would have done it probably 20 years ago but unfortunately for me, in my area they are the lowest cost cable and internet provider.
