Abstract: Mail can be sorted automatically to point of delivery level by deriving from the address including postal code on a piece of mail a suffix which together with the postal code forms routing data which uniquely identifies the final delivery address. This is achieved automatically at the Post office sorting facility by means of an optical character reader which reads the addresses on mail items and a computer arranged to generate a suffix based on the address read. The routing data is printed as a bar code on the mail item and this allows the complete sortation to be effected automatically. Also contemplated is a progressive encoding system which can be applied as bar codes by customers as desired to mail pieces. The basic data is the routing data set to which can be added a shipment number which allows automatic revenue accounting control and a piece number which allows automatic track and trace.