 Postal Service introduction of postal worksharing, ZIP + 4 and the POSTNET barcode in 1980, companies were given an incentive to sort their mail prior to inducting it at the Post Office.Today, presort and automation discounts can save companies up to 50% or more on postage—and many companies use Mail Sorters to sort both incoming and outgoing mail.Mail sorters can process up to 55,000 #10 envelopes per hour.