it would only be illegal if the party on the other end took it as payment and didnt pay taxes, or file it. even a gift tax could be applied..... other than that????????? why would it be??????
It's not illegal just a little risky. Especially if it's an international delivery because if customs decides to search your package kiss your cash goodbye.
Im not sure but i think sending cash over a certain ammount (couple thousand) internationally is prohibited.Dont know how this rule applies domestically.
it's not illegal. thats why you declare value of your package when you ship it and get an insurance (good luck claiming it, takes years to get your money back)