A method of sorting mailpieces amongst N logical sorting destinations with a sorting machine including a mailpiece conveyor that serves M sorting outlets, each of which is provided with a removable mailpiece storage tray that is handled by a tray conveyor, where M is less than N, consists in detecting that a current mailpiece to be sorted has a certain logical destination that is said to be “overbooked” and that is not associated with a sorting outlet, and in dynamically allocating to said overbooked logical destination a certain sorting outlet of the machine that is occupied by another logical destination. In said certain sorting outlet, a tray change is made and the tray extracted from said certain sorting outlet is put on standby on a loop of the tray conveyor.