Wrong. You can't ship explosives using the USPS. Like he did.
Originally Posted by Munchmasterman
341.2 Mailability, Packaging, and Marking
Explosives are generally prohibited from mailing under 18 U.S.C. 1716. The following conditions apply to the mailing of explosives:
International Mail. All explosives are prohibited.
Domestic Mail via Air Transportation. All explosives are prohibited.
Domestic Mail via Surface Transportation. Generally, explosives are prohibited. The only exceptions are for Division 1.4S toy propellant devices and safety fuses that have been approved by the manager, Product Classification, USPS Headquarters, Washington, DC, prior to mailing as stated in 341. A shipping paper is required.