I am looking to use facebook as a way for people to sign up for my app that will have user accounts so that it easier for them to connect to friends who also have the app. I have an account database set up but for this to work properly I would like to be able to use their email instead of just their ID. Is there a way to get their email that's used for facebook?
look this plugin: https://www.scirra.com/forum/facebook_t111941
when the user accept for the permission (for the app), you can get everything from the user (e-mail, uid...etc) you can also made your php code and look how to use the SDK, but the easy and fast way is this plugin