Crimes Act 1914

Hoax explosives etc.  
85Y
A person shall not cause an article to be carried by post with the intention of inducing a false belief:

(a) that the article consists of, encloses or contains an explosive or a dangerous or deleterious substance; or

(b) that an explosive, or a dangerous or deleterious substance, is or will be left in any place.

Penalty: Imprisonment for 5 years.