As Gordon Lightfoot says, in one of his songs- "can't hang on and can't let go- can't say yes and can't say no."
From personal experience:
Sent a clean, unused, but finished and fully functional small priming horn to a fellow in Quebec, who was, in fact, employed by the (Canadian) Postal Service and did, in fact, work at his local Post Office. I followed his instructions, which contained nothing about special handling.
Almost two (2) weeks after shipping it to him, he contacted me, by email, inquiring about the horns whereabouts, which, of course I could offer nothing on. After three (3) weeks, it magically appeared on his doorstep, unsecured. The original shipping box had been ripped wide open and left in that condition.
No explanation was ever supplied, nor was he ever able to determine where it had been, all of that time. He eventually concluded, to himself, that the package was probably x-rayed, thought, by the operator, to be a threat and sent to the bomb squad for disposition. Then delivered, instead of blown-up.
But hey, that doesn't mean, 'no,' right?
I'm hoping a knowledgeable horn-maker/international shipping type person will jump in here and settle this matter, but do you already know something we don't, on this topic?
Good luck!