1. A method of processing postal items in order to prepare delivery rounds by performing a plurality of sorting passes through a postal sorting machine having a carrousel of trays in which the postal items travel in trays above sorting outlets and are deposited in the appropriate sorting outlets, the method comprising the steps of: checking in the machine during a sorting pass and for each current item, data representative of an order number or rank allocated to the distribution point corresponding to the current postal item in a predetermined sequence of distribution points to run through this sorting pass in order to prepare each delivery round; said checking comprising monitoring how rank varies for successive postal items in order to detect any difference relative to said predetermined sequence; wherein in response to said detection for a current postal item, the machine is controlled to cause the current item to recirculate through the machine by making this current item carrying out one complete revolution round the carrousel so as to delay its deposit in a sorting outlet.