Yahoo mail password reject loop on OSX Apple Mail fix

If you use Apple Mail (or a similar desktop app for handling email) and you’ve seen the following error message in connection doctor, or you run into the constant cycle of the app telling you to reenter your password, this might fix it.  

“Trying to log into this SMTP account failed. Verify that the username and password are correct.”

It is possible that you’re experiencing a sign in verification issue with apps that don’t support Yahoo!’s multi-step authentication system.

  1. Log into Yahoo’s website.
  2. Click on the gear thing in the top right.
  3. Choose “Account Info”
  4. Sign in (again)
  5. In the section titled “Sign-In and Security” click on “Manage your app passwords”
  6. Give it a name like “MacBook Air Laptop Mail”  and then let it generate a unique app password.
  7. Use this password in your app, and only in this app — create other passwords unique to each app you use.  You don’t need to remember the password, the point is you just generate a “one-app” password for each app that needs to authenticate. 

Full details: http://help.yahoo.com/kb/index?page=content&y=PROD_ACCT&locale=en_US&id=SLN15241