For preparing a series of mail pieces using a mail preparation apparatus, a scanner (63) scans at least a portion of a first postal item (20, 25) and generates signals in accordance with scanned patterns. A control system (31) processes the signals from the scanner into image data representing an image and compares the image data with reference data, which represent features of optical marks of a particular type that are associated to predetermined instructions for processing postal items (20, 25). If at least a predetermined extent of agreement between the image data and the reference data is found, a job setting including scanning of optical marks from further postal items (20, 25) and controlling the preparation of the mail pieces in accordance with instructions represented by the optical marks is selected. Otherwise, a job setting not including scanning of optical marks from further postal items (20, 25) is selected.