Oh poor, embattled Postal Service — your plight embodies the platitude, “We hurt the ones we love the most.” Year after year, you’re trotted out as the country’s favorite federal agency. More than 70 percent of people sing your praises. Your fan club is so big, you even have your own merch collabs; your insignia has adorned hats and hoodies, from Forever 21 to Vans. But love doesn’t keep…