Can I get any info about my iTunes Connect customer? Regarding in-App (or other) purchases, is there any info available about the customer for a given transaction?

So far I've only found reports without any info on the customer.

It's important because how can we handle any customer requests in email without knowing if he/she has bought anything at all from us?
I don't clearly understand if you're using iOS or OS X, but you should receive a receipt from Apple servers with a lot of information about the transaction, including info about the customer. You need to validate this transaction in order to confirm an in-app purchase. more info : https://developer.apple.com/library/ios/releasenotes/General/ValidateAppStoreReceipt/Introduction.html