It's sad to hear that, Andre. But it's no surprise to me. I face the same problems in Switzerland.

I usually trade or sell dice and you know, casino dice are 3/4" (=19,05mm). To send them as a letter with a limit of 20mm, I can't use a padded envelope because it would exceed that limit. When it is thicker than 20mm the costs to send one pair (!) to the US will raise from $ 2.35 to $ 14.85 airmail !!!

One month ago I sent two envelopes with chips and dice to the US. As a decent citizen, I put that green customs sticker on the mail. Now it seems that only thiefs have an advantage of those stickers since both letters were stolen and never arrived! I complaint at the post office, but the only answer I got was, that I should send my stuff with registered mail next time - at additional costs of only $ 4.68 per letter.

Now you will understand why my post has such a subject line!