Is mail out one word or two

In American English, "mail" is often used as a single word to refer to the system of sending and receiving letters, packages, and other items through the postal service.

However, in British English, "post" is often used instead of "mail", and "post out" is a common phrase used to describe sending something through the postal service.

So, to answer your question:

• In American English, "mail out" is often considered two words.
• In British English, "post out" is often considered two words.

But it's worth noting that both "mail out" and "post out" are widely used and understood in both American and British English, so the distinction is not always observed in practice.