Yahoo account settings window : no way to enter password.
Then when trying to connect, em Client report a connection error (no kidding !)
Here are two pics: one account with Bouygues tel. and another with Yahoo to show the issue. 
Hi Bren,
When setting the Yahoo account, you will get an OAuth window to finish the setup. Did this window pop up during the account config?
Russel
Honestly I don’t remember.
But, from design point of view, it’s unbelievable the client fail to connect and absolutely did not ask for username/password resubmission. I never seen that before.
Hi Bren,
That’s because Yahoo mail moved to OAuth and the authentication is finished in the external window. Please try the configuration again and now when you see the pop-up OAuth window, fill the password in.
Russel