The only reason I said UPS is because of quicker more professional service which I've witnessed. I can't even count how many times USPS has lost a box in the mail. Believe me, it happens alot. Being a mod I get lots of emails complaining about sources when in reality they should have complained about USPS. I've received UPS shipments from within my own country and from overseas countries, never with a problem.
I may be wrong on this, but I thought that Postal Inspectors could open packages! Remember that source that everyone thought that they got scammed by him until they received a letter from the Postal Inspectors saying that they had their money! Maybe they did get a warrant, but nothing of a warrant was mentioned. Who knows!
Either way, since USPS has lost 2 boxes which were sent to me and have NEVER made a delivery to me ontime; it has left a sour taste in my mouth.