I had a problem with my Mac mail account and therefore I deleted some 4 keychain entries from my Keychain Access that were related to mail. I added a new one:
I tried to add my Yahoo account again, but this happens:
What can I do?
Yahoo has added more security and so does not work with a simple IMAP login by default.
Yahoo's information is here
I think to use MacOS Mail you need to follow step 3
While changing or upgrading your third party applications, you can temporarily give them access.
- Sign in to Yahoo Mail.
- Go to your "Account security" settings.
- Turn on Allow apps that use less secure sign in.
Caution - Do not use this setting as a permanent access method. It is intended only for temporary access while you switch or upgrade to a secure application. Remember to turn it off afterwards.