Facebook Graph API: Have extended permission, need something odd

So, I have a FB app already, and when people connect I ask for the extended permission "email" and that is all well and good. I save the email and can get a list of their frien开发者_运维技巧ds' ids and basic profiles.

I want to know if there is a way for me to figure out which of their friends have allowed their email to be visible to people/friends/public (not my app) and then get that email so I can give back a list of people they can connect to.

So, let's say you have 12 on facebook, and of those 12, 4 have allowed anyone to see their email. I want to give you those 4 emails because they have allowed them to be publicly/friend visible. Other than those, I'd have to set up a custom "request permission to know your email" kind of thing.

It seems as though it's not possible, but I just wanted to make sure.

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We don't allow access to friend email addresses for obvious privacy reasons. You have to explicitly ask for this from each user.