By sending payment receipts to your clients, they'll receive an email with a receipt attached as a PDF.
To do this, when recording a payment, activate the Email Receipt option:
You can also activate this Email Receipt option during the reconcile process:
If you want to look up previous payment receipts, you can find these in the Transactions and Payments Received areas, with the green icon as seen below:
Tip: if you want payment receipts to be automatically emailed to your clients for online purchases through the Client Area or Mobile Apps, then enable this option in the Client Area Settings: