Had the same issue a few weeks ago. Yahoo thought my account was hacked so they locked the account. I got the same errors till I logged into my account on my PC and changed the password.
Don't bother set up with Yahoo email with any iOS devices. There are so many issues with Yahoo email like asking for password too many times.
Don't bother set up with Yahoo email with any iOS devices. There are so many issues with Yahoo email like asking for password too many times.
Well it seems Yahoo loves you iVegas and Buck987. Good for you both.
Any chance you have two factor authentication enabled? You have to generate an application specific password for iOS Mail.