The present subject matter involves a system and method for producing and processing electronic transactions, including electronic checks, in a secure manner. In various embodiments, a secure server provides an electronic check service that maps payees to participating lockbox service providers and provides electronic payment instructions from the payor to the lockbox service providers to process payments to the payees. In various embodiments, a check is printed to fulfill Check21 Act requirements, electronic images are obtained of front and back of the printed check, and check image pairs are created of the electronic images of the front and back of the printed check. In various embodiments, paper items are processed where the electronic check service does not find an electronic deposit match. In various embodiments, the electronic lockbox files are used in a secure electronic payment platform that assists in the generation of electronic checks.