Abstract: An automatic sorting and stamping apparatus includes a supply section to which a stack of mail items including standard-size items and nonstandard-size items is placed. The supplied mail items are transferred to a sorting and stamping section along a transfer path extending through a plurality of processing units while being applied with desired processes thereby. The transfer path is constructed by a plurality of conveyors whose operations are controlled by a control section. The control section stores various control values for determining the operations of the conveyors. One of the control values, which is suitable for processing the mail items of the supplied stack, is selected in accordance with the ratio of nonstandard-size items to all mail items forming the supplied stack. The conveyors are driven, based on the selected control value.