I was setting up my Yahoo account in the Windows Mail App. I received this from Yahoo:

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Hi Rich,

Someone attempted to sign in to your Yahoo account (xxxxxxxx) from an app that doesn't meet Yahoo's security standards. We blocked this sign in attempt, which was made on:

Thu, Aug 4, 2016 8:14 PM EDT from United States.

If you were trying to sign in, then please take one of these actions:

Option 1 (recommended): Use mail.yahoo.com or the Yahoo Mail app for Android and iOS to more securely access your account.

Option 2 (not recommended): If you still want to use an app that uses less secure sign in to your Yahoo account:

  1. Click here: https://login.yahoo.com/account/security#other-apps[TABLE]
  2. Turn on "Allow apps that use less secure sign in"[TABLE]
  3. Go back to your existing email application and sign in to your Yahoo account again.

Using apps that don't meet Yahoo's recommended security standards may leave your account more vulnerable or less secure.

If you did not try to sign in, then click here https://edit.yahoo.com/config/change_pw and change the password for your account.

For more information, visit our help page at: https://help.yahoo.comkb/sln26418.html.