PHP支付宝快捷登录返回的参数中没有email是怎么回事？

返回的$_GET

Array
(
[is_success] => T
[notify_id] => RqPnCoPT3K9%2Fvwbh3I75K66XBRnb6QknkOgu5M%2F97vZCbkCj%2BCT%2B7aYHSgU8dum9%2B9s2
[real_name] => 罗某
[token] => 201311191d99cb70290543409014de7ff1c2648a
[user_id] => 2088002108815444
[sign] => b0509cf53f1539db0451a4a50c9df7df
[sign_type] => MD5
)