1. A method of sorting mailpieces in a plurality of sorting passes in a postal sorting machine ( 10 ) provided with sorting outlets so as to sequence the mailpieces in the sorting outlets for delivery in the order of a delivery round, in which method delivery points defining the delivery round are grouped together into disjoint subsets of delivery points, and in which method, for the various sorting passes, the delivery points of each subset are associated every time with a common sorting outlet, said method being characterized in that statistical data ( 11 ) is retrieved from a memory of the machine, which data is associated with respective ones of said delivery points, and is representative of the volume of mail delivered in association with the delivery point in question, and in that successive delivery points are grouped together ( 42 ) into a common subset of delivery points by taking account of said statistical data associated with said delivery points.