It's called an address label, they go on the boxes.
The boxes going international go through customs on site at the UPS hubs.
The NSA could achieve this by accessing the packages at customs without alerting UPS directly.
The would only have to break out an NSL because we can. to make it less of a hassle, or just to flex muscle.
Really an NSL would be detrimental to secrecy, the NSA is clearly aware that secrets keep better when you
*don't tell anyone*
Rather than when you ask them to keep it on the down low.