To process large stamped letters, machine readable large letters are placed with the stamp facing upwards in a sorting station on a conveying means that leads them to further processing stations, has a reference edge in the conveying direction and is inclined in the conveying direction. The letter edge parallel to address lines, in proximity of which the stamps are located, rests against the reference edge. The stamps are automatically cancelled by a canceling device arranged over the leading-away conveying means and at a lateral spacing from the reference edge which corresponds to the spacing of the stamps from said letter edge. The large letters are then rotated through 90° as they are conveyed onwards with the shorter letter edge resting against the reference edge, by a locally fixed rotation element, so, like the standard letters, they rest with their longer letter edge on the reference edge, as is required for further processing.