step 22 to direct the mailpiece towards a sorting outlet of the machine 1 that is identified in the sort plan for storage in a tray 5 if the logical destination of the current mailpiece is overbooked in step 21 then in step 23 the unit 7 acts on the basis of the instantaneous or forecast occupancy levels of the sorting outlets of the machine to determine an outlet to be re associated e g the sorting outlet having the lowest occupancy this level of occupancy can correspond to a rate of filling of the tray the sort plan in the memory of the sorting machine is then updated dynamically in step 24 so as to associate the logical destination that is overbooked with the sorting outlet having the lowest occupancy that has been determined in step 23 at the same time in step 24 the logical destination that was previously associated with that sorting outlet has gone to an overbooked state in the sort plan so that any mailpieces present in the conveyor 3 that have that logical destination are then put into re circulation by the unit 7 in the standby loop of the conveyor 3 the unit 7 thus suspends unloading of those mailpieces into a storage tray in step 25 the unit 7 also controls the.