Can you use US postage stamps to send a letter to Switzerland?

Answer 1

Yes, that is how it would work. You use the stamps of the country in which the package or letter originates. The Universal Postal Union sets the standards and coordinates the transfer.

Answer 2

That's what the stamps are for, to mail letters and packages to anyplace in the world. You have to use postage for the country of origin, in this case, the US.