In the past, the post office knocked on your door to collect the tariffs (duty). Under the new rules, the USPS refuses to accept delivery from an overseas post office unless that overseas post office pays the tariffs directly to our post office. This was something that foreign post offices were never set up to do, and the rules changed so quickly that overseas sellers never charged American buyers duty (besides, the tariffs changed on a daily basis) and therefore never had money to pay the foreign post office to pass along to the USPS.

It has been a mass of confusion. I highly recommend that nobody purchase from overseas if your package is going through the mail service. Eventually - as France has apparently done - the package will be returned to the French address, you won't get it, and the seller will be out all that postage money unless Ebay steps in and makes everybody whole. Buyers and sellers are both at a disadvantage and that package is likely not coming to you (and certainly not in a timely fashion).

I don't believe American sellers are facing similar obstacles except for the UK (and maybe a handful of other countries), which had already worked out a system for collecting VAT a couple years ago through eBay that required buyers to prepay all taxes so the packages could be received into the UK and then delivered by the Royal Mail.

International mail traffic is down 81% as a result of this new process.