Just a quick note, a PO Box is no perfect solution to having someone else open up your mail. A friend delivered meds to me, domestically, to my PO Box, and it was scanned as delivered, but the post office could find no trace of this mysterious package. Either
a) it was sent to a different PO box, and the person signed for it and kept it
b) its contents were discovered, and rather than referring it to LE, USPS just discarded the package
c) it really was just lost in the system
Either way, options a, b or c, none of them resulted in my getting my mail. It might not have even prevented a mix-up, as it could've been put in someone else's box by mistake. There are ways to mitigate risk, but there is no such thing as a foolproof mail delivery system, be it public or private.