There is a legal process, though, at least in the USA. You can get a warrant (a court order) to open a piece of mail, and the USPS isn't going to refuse to han

There is a legal process, though, at least in the USA. You can get a warrant (a court order) to open a piece of mail, and the USPS isn't going to refuse to hand it over. [technically they could, but someone would get stuck with contempt of court charges]