A mailer is an individual employed by a newspaper publisher to handle newspapers

Newspaper

A newspaper is a scheduled publication containing news of current events, informative articles, diverse features and advertising. It usually is printed on relatively inexpensive, low-grade paper such as newsprint. By 2007, there were 6580 daily newspapers in the world selling 395 million copies a...

 from the point where they emerge from the press

Printing press

A printing press is a device for applying pressure to an inked surface resting upon a print medium , thereby transferring the ink...

 to where it is loaded onto trucks

Truck

A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

 or other means of transporting the newspapers.
Preparing newspapers involves identifying the bundles by edition and inserting advertising supplements as well as the physical movement of bundles.

History

Before automation, this was a labor-intensive occupation and at its peak there were thousands of people employed as mailers. In the United States their specialization was incorporated into the International Typographical Union

International Typographical Union

The International Typographical Union was a labor union founded on May 3, 1852 in the United States as the National Typographical Union. In its 1869 convention in Albany, New York, the union—having organized members in Canada—changed its name to the International Typographical Union...

.

Early in the twentieth century there was a division between the higher-skilled typographers and the lower-skilled mailers over whether they should be represented in the same union.