 Recent innovations allow for mixed mail sorting—providing for postal discounts on letters, small parcels, flat mailers, irregularly shaped pieces, padded envelopes and even Polywrap sheets.In 2007, the USPS introduced Shape-Based Pricing which offered more significant postal discounts for mailers who sorted flat-sized mailpieces.In response to this postal change, the market responded with new low-cost systems designed specifically to support flat mail sorting for mailers who process between 500 and 10,000 First-Class flats per day.