Hauling the mail means

A classic phrase!

"Hauling the mail" is a colloquialism that refers to the act of delivering mail, particularly in a rural or remote area. It is often used to describe the task of a mail carrier or postal worker who has to travel long distances to deliver mail to individual homes or businesses.

The phrase is thought to have originated from the days of horse-drawn mail wagons, where the mail carrier would "haul" or transport the mail from one place to another. Even with modern vehicles and technology, the phrase has stuck and is still commonly used today.

In some cases, "hauling the mail" can also refer to the physical act of carrying a heavy load of mail, often in a mail bag or satchel, from one location to another.