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.

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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

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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.