Webkassa allows to enable program RRO for your business. A new feature will appear, which allows to sale/buy/return receipt creation. Submission to the client's email will be available from within the RRO.
Webkassa app is an RRO module for your system, built on OneBox.
If you're looking for a complex solution for RRO (PRRO), please follow the link "RRO for business" or "CRM system configuration for small to medium business RRO automation"