I recently received an email from Yahoo!, saying my Yahoo! account is an victim of the (many) hacks. However, I received this email in my Gmail account. I tried to see if my Gmail email address is registered in Yahoo! by going through 'Trouble signing in' in https://login.yahoo.com. It does't look like its registered.
Can someone please explain to me:
How on earth I receive the email? I never received any forwarded email from an Yahoo! account, so I am not sure if this is one.
How can I verify if I have a Yahoo! mail account?