A system for marking an edge of a mailing piece with a desired indicia, thereby permits identification of the marked mailing piece when the marked mailing piece is stacked with other mailing pieces, usually similar mailing pieces. A computer directs which mailing piece is to be marked and activates the marking process. A group of computer controlled solenoids, with each solenoid linked to an indicia imprinting marking pad, is activated for the edge marking. Each activated solenoid forces the marking pad against the mailing piece's edge thereby marking the edge of the mailing piece.