Update: the Profile Service, part of the AppCloudServices module, has been updated. It now exposes a more extensive user profile, including the user's email address. A new version of the AppCloudServices module has recently been released to the App Store, which contains the new profile service.
Oudated answer: At the time of writing, in the latest version of App Cloud Services, v.1.1.2, it is not possible to retrieve the user's email address. You can only retrieve a user's display name.
In your app, you could ask the user for any further information that you need from him/her after logging in.
Thanks for you answer, i will have to wait for a newer version.