A method for processing mail, wherein a plurality of mailing items inserted into insertion places are collected and subsequently transported in a container to postal centers where they are sorted in sorting devices according to postal categories. The invention is characterized in that the mail is placed in transport containers which are transported to unloading areas in postal centers. When the transport container is filled and/or during the transportation of the container to the postal centers, random partial pre-sorting of mail takes place according to postal categories so that, when, the mail is removed from the containers at the unloading areas, it is in the form of piles formed by the predetermined pre-sorting method and sorted according to the postal categories, whereupon it is guided to subsequent processing stations according to said postal categories.