Tampering with the US postal service is a federal crime.
18 U.S. Code § 1701.Obstruction of mails generally
U.S. Code
Whoever knowingly and willfully obstructs or retards the passage of the mail, or any carrier or conveyance carrying the mail, shall be fined under this title or imprisoned not more than six months, or both.
(June 25, 1948, ch. 645, 62 Stat. 778; Pub. L. 103–322, title XXXIII, § 330016(1)(B), Sept. 13, 1994, 108 Stat. 2146.)
The term in use here is retard, you retard.