Did you know that...
in Australia, Canada and the United States, mail is commonly used both for the postal system and for letters, postcards and parcels? In New Zealand, post is more common for the postal system and mail for the material delivered. In the United Kingdom, post prevails in both senses.
Curiously, the British postal service is called Royal Mail, while the American, Australian, and Canadian national postal services are called, respectively, United States Postal Service, Australia Post, and Canada Post.
Also, such fixed phrases as post office or junk mail are found throughout the English-speaking world.