The Post Office was established before telegraph. Before the phone and Internet. Before 37 of the states were part of the Union. Perhaps we don't need to subsidize it to the degree we do anymore?

(subsidize: not only do we incurring retirement obligations from the general fund, we charge the same amount to deliver a letter to rural Alaska as we do to a place across the street)

We could cut costs by reducing mail delivery frequency country-wide and more in costlier areas. In the age of satellite Internet, the need for delivering a physical thing quickly is not something we need to federally subsidize (argument for slowly: yes). In my suburban area I'd be completely unaffected by 2/week delivery. People in rural areas need to pay the cost of living rural now that we don't have anyone subsistence farming.