Apple will email receipts for purchases made on an account. As for whether or not that one is valid, it may or may not be. When encountering something like this it is best to use a means Apple provides for independently checking the validity of the claim.
Click on the link for directions about how to see your purchase history in the App Store or iTunes Store [mobile device, computer, or web] --> View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support
- Does not include purchases made by others under Family Sharing; those have to be checked from their accounts.
- Web: "To see charges from older purchases, you might need to look at your purchase history in Settings or the App Store."
- iOS device or computer: If you want to see purchases that you made more than 90 days prior, "tap Last 90 Days, then select a different date range."
If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement, click on this link --> If you see 'apple.com/bill' on your billing statement - Apple Support