If you are thinking about your Yahoo and AT&T email account being merged or not then take a look at these given measures -
1. When you are able to access your Yahoo account with the use of your AT&T email address.
2. You are getting both accounts' emails in one place.
3. When you are login into your Yahoo account and you get redirected to the AT&T sign-in page.
4. The login details of AT&T are working for your Yahoo email account as well.
5. Resetting the password for any one of the accounts will change the password for the other too.
