Gemma
I’m sorry I don’t understand your question. If you are using an iOS app to get the data you should be able to get it from the Apple library the first time only too (I am not an iOS dev so do not know the code for this). When you send the token to your own backend, you can exchange that token with Apple and the first time you do this after decoding the JWT token the ‘sub’ category will contain the email but if you have tried before for that user it won’t.