To further point out the ridiculousness of preventing local post offices from sorting mail: For 8 years, my landlord and I had PO Boxes at the same small town post office. You'd think one could just hand rent to the teller, who my landlord and I both knew by name, so she could walk the ~8 feet and put it in my landlord's box. But that wasn't allowed. Delivery to the same post office the letter was mailed from took a few days to a week because they had to send it off to a sorting center and wait for it to be sent back.