The present subject matter relates generally to a system and method for controlling functions in a mail sorting system based on gap length measurement and tracking. The system and method includes a plurality of sensors located along one or more mail piece transport paths. The sensors are used to collect data regarding the gap length between each mail piece transported through the system. The gap length data is processed and stored within a controller/processor that uses the gap lengths to control the operation of one or more devices within the mail sorting system. For example, the gap lengths may be used to control the operation of a diverter, a printer or any other electromechanical, hardware or software device. The gap lengths can be used to trigger and/or inhibit the operation of the one or more devices.