How to access to account mail by platform

Unity

Android

• https://stackoverflow.com/questions/2112965/how-to-get-the-android-devices-primary-e-mail-address
• https://www.assetstore.unity3d.com/en/#!/content/38872/
• https://www.assetstore.unity3d.com/en/#!/content/44553
• https://www.assetstore.unity3d.com/en/#!/content/26816