1. A method of sorting postal items in a plurality of sorting passes using at least one sorting machine ( 1 ) having sorting outlets ( 3 ) constituted by bins ( 4 ), each postal item having a surface carrying a destination address (A) suitable for being recognized in the sorting machine by a data processor system ( 10 ) for automatically recognizing addresses by OCR and/or video coding, the method being characterized by the following steps: during the first sorting pass, loading interchangeable empty bins into the sorting outlets of the machine, each bin carrying a bin identification number (Bin_ID), and communicating ( 30 ) the identification numbers of the empty bins to the data processor system; forming ( 31 ) an image of the surface of each postal item as each item passes through the sorting machine, said image including the address information of the item, and deriving ( 32 ) from said image a digital fingerprint (V_ID) which is an identifier of the postal item, and as said items are directed towards the sorting outlet bins, recording ( 33 , 34 ) in the data processor system the digital fingerprints of the postal items in association with the identification numbers of the corresponding sorting outlet bins, and counting the postal items sent to each sorting outlet bin; and during the second sorting pass on the same sorting machine or on another sorting machine, loading the full sorting outlet bins into the sorting machine while informing ( 40 ) the data processor system of the identification number of each loaded full bin, building up a database (DB) in the data processor system, the database comprising a collection of digital fingerprints as recorded during the first sorting pass in association with the sorting outlet bin identification numbers and corresponding to the identification numbers of the full bins that are loaded into the machine as postal items taken from the loaded full bins pass through the sorting machine, forming ( 43 ) an image of the surface of each current postal item, which image includes the address information of the item, deriving an intermediate digital fingerprint from this image of the current postal item, assessing and scanning ( 44 ) the database in order to detect a match between the intermediate digital fingerprint of the current postal item and a digital fingerprint in the database, and updating ( 51 ) the database by counting ( 46 , 47 , 48 ) the matches obtained for each loaded bin and the consecutive accesses to the database made without obtaining a match.