I am using thunderbird 115.10.1 (64 bit)

I finally got through to Yahoo. There is an undocumented step to get imap to work.

• Log into your yahoo account mail.yahoo.com
• go to account info
• go to secuity
• get an app password for Thunderbird.
• use this password when Thunderbird tries to log in
• send a test message from your yahoo account to your yahoo account
• it seemed to ask for it twice -- use the app password the second time if asked

From then on, use the password you set up.

After the message went though , the email account re-appeared in my unified mailbox.

After doing all of that, it still worked only for one account at a time. I searched this forum for more information and found the answer. I don't know if you still need to go through all the steps above.

In server settings for the account, the connection security is SSL/TLS and the authentication method is 0AUTH2

When you send an email, it should take you to the Yahoo website where you log in and then give Thunderbird permission to use you email account.

PattiWagen - when you say "app password" does that mean you're doing this on a phone? I'm using a PC, and have about gone mad. If this can be done on a PC, whereabouts would I enter the Thunderbird app password? Thanks either way. It may be throat-cutting time soon.