A mail production system is described, the system comprising a mail finishing system for converting documents into finished items of mail ready for hand-over to a postal service, and a secure accounting system for generating accounting data relating to the items of mail produced by the mail finishing system, wherein the secure accounting system is able to generate signals to control operation of the mail finishing system. Specifically the secure accounting system is able to delay or stop operation of the mail finishing system. A corresponding method of producing mail is also described.