I have been asked many questions and here are more details 1- FB Api did not return anything when I asked for the email 2- I am not sure but I think that during

I have been asked many questions and here are more details 1- FB Api did not return anything when I asked for the email 2- I am not sure but I think that during the verification process of your account, Facebook automatically change your primary email address. All the users that had a phone number instead of their email had their old college email address that did not work anymore and Facebook deleted it from their account 3- A way to monitor the number of errors is to log all the FB Login error in your code or with Mix Panel