This is useful in the 5 percent of cases where you know the package was intercepted ahead of time. You can throw away the mailbox key, never visit that post office again, and you'll be safe because they won't know who are or where to find you. In the other 95% of cases, you won't have a clue that it was intercepted until you're standing in the post office with the package in your hand and a guy with a badge steps out from behind the counter (or pulls you over a few blocks away). If you don't get mail there regularly and only visit every few weeks, but show up the day the package is delivered, or the day after, that indicates you had prior knowledge of the package. IMO, a residential address is safer because you can passively receive the package and choose when to pull it out of the box. LE isn't going to wait around for hours or days, and at all hours of the night, for you to pick up a small amount. They will either knock on your door and see if you accept it, or not deliver it at all (in which case, it will join the ranks of the infamous missing packages). To that end, it's best not to be home when the mail is delivered. People have proposed using various light sensitive devices that can warn you when the package has been opened. They might be worth it for large orders, but it's also possible for LE to x-ray the package, discover that it contains such a device, and open it in a dark room to field test the drugs. They are also known to use needle-sized poking devices to sample the contents, which leave a hole so small that it probably wouldn't set off the device. To protect against that, you would have to fortify it with a hard internal package, which again isn't worth it for small amounts, when simply mailing the drugs in an envelope is much safer.