Perfume products are treated as flammable liquids because they contain ethyl alcohol, which is a flammable substance. Flammable perfumes are marked with hazardous warnings on the labels.
Ethyl alcohol, also referred to as ethanol, has a flash point of 63 degrees Fahrenheit. The flash point is the lowest temperature T which a substance's vapor is ignitable.
Perfumes are classified as hazardous materials for shipping due to the ethanol present in the compounds. According to the U.S. Postal Service, perfume is allowed to be sent by mail when it meets federal guidelines. The package must be sent by parcel post, must not exceed 16 fluid ounces, must be cushioned in a damage-resistant box and must be marked as "Surface Only" or "Surface Mail Only." Customers may only send one bottle per package.