WASHINGTON - The U.S. Postal Service today announced plans to begin a two year experiment of Presorted Priority Mail rate categories and corresponding discounts starting July 15. The experimental rates include discounts for three presortation options: ADC (area distribution center - a mail processing facility that represents a state or a large portion of a state), 3-digit ZIP Code prefixes, and 5-digit ZIP Code sorts. "We are seeking to make Priority Mail more affordable and offer our customers more options and greater value," noted John F. Kelly, President, Expedited/Package Services, at the time of filing with the Postal Rate Commission. In order to receive the discounts, mailers must meet certain containerization, preparation, minimum quantity, and data collection requirements. The containerization and preparation requirements may vary by mailer location. The purpose of the experiment is to measure the costs associated with mailer presortation and to determine if incentives provided by the discount structure are attractive and beneficial to the mailing community.