Last week, a Comcast support staffer helped me change my email settings to point to the new Outlook 365 server addresses. I was able to receive and send mail using my Thunderbird email client at that time. Today I am unable to receive or send, and the message received when trying is "Not an IMAP 4 server".
1. Why is this a problem now when it wasn't last week?
2. Will I be forced to use the Outlook 365 email client instead of Thunderbird to handle my email?