I would consider both of these are spam unless the user explicitly asked for it. Not "you bought something" but hitting the "yes, I would live to receive my rec

I would consider both of these are spam unless the user explicitly asked for it. Not "you bought something" but hitting the "yes, I would live to receive my receipt via e-mail" button. You can always allow the user to retrieve their receipts later on your site by logging in or "accountless" by sending a code to their email. In-person interactions seem to have no issue with buttons for "no receipt, email receipt, print receipt, text receipt."