There was an old show about a spy who got outted,
well he sent a pipe and a sprinkle of fertilizer to his old bosses so they would stop ignoring him and pick up the phone.

This seems just as hoakie.
I mean, the timing mechanism to actually do the thing they said was being done is extremely complicated. USPS never delivers on time.
And so, you would need an "open the box" trigger... but, USPS does not handle packages with care...
So, where are all the postmen being blown up every week?

And the one that keeps falling over