To me, this looks like a Yahoo problem. In doing a web search, I see this question has been posted on many websites with other email clients. I was easily able to duplicate the problem.

It does look like a yahoo problem. Will post more information shortly.

I'm interested in knowing what is going on. I'm still not able to send/receive email on the yahoo accounts and I get the message "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.gmail.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'." Thunderbird isn't giving me the option of entering my password.

I haven't changed anything in Thunderbird and I can login via the web directly. It's been working fine for a long while.

ETA: Whatever is happening, it's now gone to my outlook.com account and my gmail.com account. I'm reading all my mail on the web now.

The other 2 accounts (gmail and outlook) also started failing. I ended up closing Thunderbird and it crashed.

This has fixed it for many:

First, generate an app PW - see https://help.yahoo.com/kb/SLN15241.html.

Then go to TB menu > Account Settings > Server Settings and set the following:

- Server Name: export.imap.mail.yahoo.com - Port: 993 - Connection Security: SSL/TLS - Authentication method: Normal password

On the left column, scroll down and click 'Outgoing Server' and edit the Yahoo entry:

- Server Name: smtp.mail.yahoo.com - Port: 465 or 587 - Connection Security: SSL/TLS - Authentication method: Normal password

Finally, go to TB menu > Settings > Privacy & Security > Passwords

- click the 'Saved Passwords' button and edit the Yahoo entry to add your new app PW

After that's done, try logging in.

BTW, this fix is mentioned in the related [bug](https://bugzilla.mozilla.org/show_bug.cgi?id=1997062).

Yeah, I believe I did that when I first set this up several years ago. I'll give it a shot but it doesn't answer why Outlook and Gmail stopped working, as well.

Re-generating the app password and using the steps above fixed the problem. The server (export.imap.mail.yahoo.com) also had to be changed. In the instructions, I would move the server step to last because you have to restart TB when you change the server info.

I'm not sure why TB was working all this time and it suddenly decided to stop. For what it's worth, I searched on the 'Edge: Too Many Attempts' and the link cited in your answer wasn't in the first few pages of results. If there is a way to pin this or bump the link, it could be helpful. Or maybe since it seems to be a recurring problem, add it to a FAQ?

Thanks for your help.

Re-generating the app password and using the steps above fixed the problem. The server (export.imap.mail.yahoo.com) also had to be changed. In the instructions, I would move the server step to last because you have to restart TB when you change the server info. I'm not sure why TB was working all this time and it suddenly decided to stop. For what it's worth, I searched on the 'Edge: Too Many Attempts' and the link cited in your answer wasn't in the first few pages of results. If there is a way to pin this or bump the link, it could be helpful. Or maybe since it seems to be a recurring problem, add it to a FAQ? Thanks for your help.

Thanks for the tip. It's not a TB issue; Yahoo is blocking some OAUTH connections.