I guess the closed borders mean significantly less flights into those countries, therefore significantly less room in the cargo holds for mail. My guess is carg

I guess the closed borders mean significantly less flights into those countries, therefore significantly less room in the cargo holds for mail. My guess is cargo planes are still flying in goods, but they cost a lot more so that USPS has decided it's losing too much money... As far as I know, passenger flights find out the weight of their passengers and luggage, and then sell the remaining space/weight allowance for cargo, I wonder if that's how most overseas mail are delivered. For time-critical or heavy stuff this system is a bit random, obviously, so if you want to deliver something heavy you'd buy space in a cargo plane instead...