The "change" is to require everyone to use oth2 authentication. you could have just changed the authentication method in server settings. But you provider has done such an exemplary job they have told people to delete their accounts, and in the case of most POP users all their mail archives as well.

Now we have oAuth, it is a web based authentication method, and it is all being run out of a yahoo server. I have no idea what the authentication page will show as it is being served directly to you by the authentication server. If really has nothing to do with Thunderbird.

Did you put in your compuseve credentials into the yahoo page. I think that is probably all you have to do.

Thanks for the reply Matt. I started a Yahoo account, using my compuserve email and password. When I try to set up the account from Thunderbird, to download my compuserve email, it still doesn't work. A couple of days ago, I called Compuserve Support. I explained my problem. One of their tech people took control of my computer and tried to set up the account using all the right settings for imap incoming and outgoing servers (using AOL addresses, aol.com. She did the settings using the manual configuration, and put in the right authentication method, etc. And still it would go to yahoo sign up. She called up AOL tech people and they told her it should be going to aol.com. It wasn't. As I said, I set up a Yahoo account. I tried to set up the account again a few times. I got messages from Thunderbird saying there were problems with authentication. I tried to adjust the settings on my own. Now all I get when I try to set up the account, I get a Thunderbird message saying server already exists.