Abstract: The printing and post-processing system according to the invention provides as a compact integration unit a computer unit (10) for commanding with programs each component of the system for selective and controllable operation, a printer unit (12) selectively operable with program to print the sheet to be mailed, a folding unit (16) for folding the sheet with different folding modes including wrap and Z form foldings, a conveyor unit (18) for conveying the folded sheet with a selectively added enclosure to the enveloping or storing position, an envelope tray unit (20) for stacking a plurality of envelopes and discharging the same by piece, an insertion unit (22) for meeting the envelope with the folded sheet for subsequent insertion thereinto, a sealing unit (24) for sealing a flap of the envelope, a receiver unit (26) for receiving and storing the sealed envelopes therein, an enclosure supplying unit (28) for selectively supplying an enclosure to the conveyor unit.