1. A method of controlling a sort processing device of a sort processing system to process an envelope housing a document, the method comprising steps of: sensing the orientation of a magnetic character on the document, using a magnetic ink pattern recognition detector, during the transport of the envelope housing the document through the sorting system; processing, by a sort control processing device, the sensed orientation of the magnetic character; and controlling a sort processing device in response to the processing of the sensed orientation of the magnetic character to process the envelope.