A mail sorting and sequencing system having a number of DPP units cooperating with one another to sort and sequence mail items of three different types of mail. Each DPP unit having: a conveyor system wherein a number of trucks travel along a path; at least three truck feed units communicating with the conveyor system and receiving mail items of a respective type of mail; at least one accumulating device cooperating with the conveyor system to receive mail items released individually by the trucks; and a buffer unit for housing groups of mail items from the accumulating device.