All kinds of poison, and all articles and compositions containing poison, and all poisonous animals, insects, reptiles, and all explosives, hazardous materials, inflammable materials, infernal machines, and mechanical, chemical, or other devices or compositions which may ignite or explode, and all disease germs or scabs, and all other natural or artificial articles, compositions, or material which may kill or injure another, or injure the mails or other property, whether or not sealed as first-class matter, are nonmailable matter and shall not be conveyed in the mails or delivered from any post office or station thereof, nor by any officer or employee of the Postal Service.

The Postal Service may permit the transmission in the mails, under such rules and regulations as it shall prescribe as to preparation and packing, of any such articles which are not outwardly or of their own force dangerous or injurious to life, health, or property.