How to obtain ALL e-mail addresses for a Google Account?

Question

Hi there,

I'm building a web application using DotNetOpenAuth to do the authentication with OpenId and Google Accounts. My web application should not allow just any Google Account; instead I will have a table storing some allowed e-mail addresses, and if the user logs in with an e-mail contained in this table the login will succeed.

My problem is that users generally have more than one e-mail address connected to their Google Account (especially transitioned Google Apps users which often have domain aliases). I need to check all of them to see if the user is allowed to login.

I do the following to get the primary e-mail:

protected void openId_LoggedIn(object sender, DotNetOpenAuth.OpenId.RelyingParty.OpenIdEventArgs e) {
    string test = e.Response.FriendlyIdentifierForDisplay;
    var fetch = e.Response.GetExtension<FetchResponse>();
    if (fetch != null) {
        string eMail = fetch.GetAttributeValue(WellKnownAttributes.Contact.Email);

        var usr = db.SystemOperators.SingleOrDefault(so => so.EMailAddress == eMail);

        if (usr != null) {
            FormsAuthentication.RedirectFromLoginPage(usr.EMailAddress, false);
        }
    }
}

protected void openId_LoggingIn(object sender, DotNetOpenAuth.OpenId.RelyingParty.OpenIdEventArgs e) {
    var fetch = new FetchRequest();
    fetch.Attributes.AddRequired(WellKnownAttributes.Contact.Email);
    e.Request.AddExtension(fetch);
}

The FetchResponse does not return a collection of addresses, just the primary. Anyone have any ideas?

Thanks in advance!