Previous discussion: Yahoo! Mail Set up on Apple MAIL
I followed the instructions posted in a previous discussion and it does not work with macOS Sequoia. There is no option to add the yahoo server and port settings. And as usual Yahoo was no help.
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Troubleshooting Note: App Password
If the simple sign-in fails or you receive an "Authentication Failed" error, you will likely need to generate a one-time App Password from your Yahoo account security settings and use that instead of your regular password.
To use an App Password:
Generate App Password: Log into your Yahoo Mail account via a web browser. Go to your Account Security settings and look for the option to Generate and manage app passwords. Create a new password for "Apple Mail" (or another app name) and copy the 16-character code it provides.
Add Account Manually in Apple Mail:
Go to System Settings > Internet Accounts > Add Account.
This time, choose Add Other Account...
Select Mail Account.
Enter your Full Name, your Yahoo email address, and then paste the 16-character App Password into the Password field.
Click Sign In or Next. Apple Mail should automatically detect the correct Yahoo server settings.