The current rate case may mark a revolution in how the U.S. Postal Service determines rates. For the first time, the proposed rate structure would consider both shape and weight. The planned increase averages 8.5 percent, but items that require hand processing would see increases of up to 90 percent. Today's machines can read an address, print a barcode and sort more than nine letters per second. And technology has largely automated the processing of handwritten letters as well as flats and parcels. But the USPS realizes these efficiencies only when mail works with these tools. That's why the proposed rate structure, expected to take effect in May, offers price incentives to encourage automation-friendly mailing. The plan penalizes packages that require manual processing when more efficient options exist. As the item gets lighter, the rate increase percentage soars. A two-ounce letter, for example, actually decreases 2 percent to 62 cents, but postage for a two-ounce First Cl