how to verify google+ email is a gmail/google apps account

Question

I am connecting through OAuth2 to google+ using python to get the basic information of email/profile and to be able to sync email accounts with it. Now the only issue I am having is that some users use an email in google+ that is not a gmail/google apps account, meaning, I can't really use that connection to sync the user emails into my system.

Is there a way to verify that an email is a gmail/google apps account?