Also, to the extent that mailers send broadly to all destinations, a system of this kind would not change postage bills, it would just increase some rates and decrease others.
Destinations that are broadly used will have lower prices. 
mnli hypothesis: Destinations that are broadly used will have lower prices.  premise: Also, to the extent that mailers send broadly to all destinations, a system of this kind would not change postage bills, it would just increase some rates and decrease others.