title: How to detect if an email is a Google Account?
body: <p>Me and some guys here are working on an start up. We are currently using Google OpenID API to manage registration and login to our app, but we want to migrate to a easier user registration model. And for this, we need to know if there is a way we can detect if an email (not gmail) is already a Google Account. Is there a way to get this info from the Google Single Sign-on API?</p>
  
  <p>Previous thanks for your help! :)</p>