When a payment is registered a confirmation mail should be sent

[Johan Gustafsson]

User request.
When a payment for a registration is registered a confirmation mail should be sent to the person making the payment to inform them that their payment has been received.
For payments by invoice this should be done when the paid by invoice button is clicked in the view registrations tab. Payments done with credit card needs a separate implementation. Maybe how to solve this depends on how the payment service functions?