Retrieve Google Calendar owner's email address

Is it possible, with the Google Calendar API / Zend Gdata, to get the user's google email address, after he successfully authenticated with AuthSub and I have an access token?

I have a problem with some users having multiple Gmail and Google Apps accounts, and then not remembering which one they've used to Sync with my service and having the impression that the sync doesn't work. I'd like t开发者_开发百科o display them the Google Account they have first authenticated with.

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Have you tried the experimental settings API? It looks like it returns the user's name and email address in the author section.