How to return email address when auth an OpenID?

I'm trying to build a login form using OpenID Auth. I'm using sample code from: http://openidenabled.com/php-openid/ But I only get user's email address when auth with account o开发者_开发技巧n myopenid.com I want get returned email when auth link "google.com/accounts/o8/id" How can I do? Thank you very much.

There's absolutely no guarantee that a particular OpenID will be backed up by an email address.

To get that level of user data, you'll need to look into the "persona" part of the OpenID system

You must use the AX extension instead of the Simple Registration extension. You also must "require" the email attribute instead of marking it as optional.

Special requirements for Google.