Mailer (noun)

1. A container or package used for mailing or shipping items, such as letters or parcels.
2. A person or company that sends out large amounts of mail, such as advertising or promotional materials.

Origin:

The word mailer comes from the word "mail" which refers to the process of sending letters, packages, or other items through the postal system. a mailer is typically a container or package used for mailing or shipping items.

Examples:

1. I used a bubble mailer to send the fragile item.
2. The direct mailer was sent to thousands of households.
3. The package is a special type of mailer to protect the contents.
4. He used a mailer to send the gift.
5. The company is a major mailer of catalogs and flyers.