Why is macOS is unable to verify my Yahoo user ID
In Apple Mail, add a new account and after entering a full name, email address and password, hold down the Option key. The Create button will change to Continue, allowing one to manually configure the account settings.

Use the following settings:

Incoming Server - imap.mail.yahoo.com

Outgoing Server - smtp.mail.yahoo.com

Incoming Port - 993 (requires SSL)

Outgoing Port - 465 (requires SSL/TLS)

Username: full email address (example: bill@yahoo.com)

Password: the password you login to Yahoo with


Make sure to identify four mailboxes as special: Drafts, Trash, Sent and Bulk Mail (Junk).

For example, in the left pane under the heading "On My Mac" under the Yahoo account, select the Draft folder. Then on the menu bar select Mailbox > Use This Mailbox For > Drafts.  Do this for the other 3 mailboxes to make sure your mail gets sorted correctly.