The sorting device according to the present invention has at least one mail item buffer receptacle, a number of storage pockets for mail items arranged one after another and circulating continuously in a conveyor belt and moved past one or more loading stations. Below straight transfer sections of the conveyors fixed intermediate storage receptacles open at the top are arranged to accept one or more mail items from the loaded storage pockets to be opened under control in the transfer sections. On a transport path below the intermediate storage receptacles there are also continuously circulating mail item containers open at the top as sorting end points assigned to the destination addresses or destination address groups. In the mail item containers the mail items are unloaded downwards in a horizontal position in accordance with their read destination address through controllable opening of the relevant intermediate storage receptacle at the point, in which the mail item container assigned to the address is located in the corresponding position below the intermediate storage receptacle with mail items for this mail item container.