I am not sure if there was an Email template setting for receipts previously as i never email them.
Anyway this setting is not available in the latest version 17.10.0 either.
Also, in receipts, the email address does not auto-populate with the email id set for a customer or supplier.
It may also be taken into consideration that the email templates should be different for a payment received receipt and payment made receipt.
While most business will not have the need to send a receipt for payment made to a supplier, it will be better if the receipt mailed to them do not show the expenses incurred for the payment, like the bank charges. so i hope @lubos considers this if there is any plan to make this available in the coming days.