What's your version of TB, and are you using pop.mail.yahoo.com on 995 and smtp.mail.yahoo.com on 465; SSL/TLS, OAuth2 authentication, User Name = email address?

sfhowes, I did not have all that. But it still responds server error, as always. OAuth2 was not accepted, had to be normal pw. I've tried everything manually in the past.

But still why doesn't TBird configure it automatically as it used to before 2018.

It should configure with the correct settings if you have a recent version (currently 78.12). I don't know if it matters if the address is @yahoo.ca or @yahoo.com. What exactly is the error (post a screenshot if possible)?

I was sticking with 2018 v78.7.1 to test something. It shouldn't matter unless you specifically know of a fix applied. Now I've updated and same server error. To test TB's configuring I'd have to create a new account. I'm not up to all those contortions based on presumptions, I don't believe it will make a difference. I'd need some concrete explanations.

Concrete explanation 1. Yahoo require oAuth authentication or the use of a mailkey. https://login.yahoo.com/accountkey/setup or application password in conjunction with 2 factor authentication https://au.help.yahoo.com/kb/generate-manage-third-party-passwords-sln15241.html. They no longer accept a Normal password and have not for some time.

Concrete explanation 2. Thunderbird supports authentication to yahoo servers using oAuth authentication and has for a number of years although POP authentication support has only been in place since Yahoo required it If you are adding the yahoo server for the first time you will have to change the server name and close the account dialog/ tab and reopen it to make the list offering account authentication refresh to display oAuth. It is not offered for all servers, only specific ones and the list is populated when the page loads.

It is about 5 years since I filled the bug to enable Yahoo oAuth https://bugzilla.mozilla.org/show_bug.cgi?id=1293958 and then the automatic configuration data was updated. https://bugzilla.mozilla.org/show_bug.cgi?id=1474694

Concrete explanation 3. Most folks that have issues with oAuth have turned of cookies, despite them being allowed in the default settings. They are required for oAuth.

Concrete explanation 4. Your error even with the relevant information blanked shows your user name is not set as you email address as yahoo stipulate. https://au.help.yahoo.com/kb/SLN4075.html as the text is not long enough to include an @yahoo.ca part.

Concrete explanation 5. It would appear yahoo.ca has never been added to the auto configuration process. I will see what can be done about that going forward.

I was sticking with 2018 v78.7.1 to test something. It shouldn't matter unless you specifically know of a fix applied.

Now you talk about 2018 and V78. One of those things can not be correct V52 was released in July 2017 V60 was released in August 2018 V68 was released in August 2019 V78 was released in July 2020.

So what versions of Thunderbird do you actually have installed? V60 has support for imap accounts on Yahoo, but POP support for oauth was not added until V68 https://bugzilla.mozilla.org/show_bug.cgi?id=1538409

V68 auto migrated yahoo users to the correct oath authentication https://bugzilla.mozilla.org/show_bug.cgi?id=1606339 to cope with the changed policy of yahoo.

Old software versions are not supported. So your way forward is most likely a new version of Thunderbird.

For now Correction: Filehippo gave the date of v78.7.1 as June'19. But I'm up to date now. I've tried @yahoo.ca and OAuth2 and it just gives me a timeout. Also tried server .ca. The female Yahoo CEO kindly did away with personal support. Otherwise this might be solved. I don't know if they informed us of changes or updated their site.

What happened now: TBird showed a panel to agree to Yahoo's terms on OpenID and OAuth. This opened the gate for all my past mail.

I guess it's due to OAuth. Using server .com. Thanks.