What goes out when someone pays, or a payment fails?

A payment receipt confirms the money landed, however it was paid — online, or a cash or check payment you recorded yourself. A card declined on the pay page is told to the customer right there, on the page, and nothing is emailed — the invoice stays unpaid and their link keeps working. A bank payment that fails after the fact — a few days later, when the bank bounces it — gets a payment-failed note that says nothing was taken and gives them one button to try again. Both are automatic and both go from your business. A refund sends the customer a short refund notice — how much went back, on which invoice, and when to expect it (card refunds show within 5–10 business days; a cash or check refund is simply recorded) — with nothing to click, because nothing is owed. One notice per refund, whichever way it was issued.