CATALOG..Mailer Shipping BoxA mailer shipping paper box is a type of packaging that is used to send items through the postal service. It is usually made out of corrugated cardboard and has an opening on one side, which allows the item to be inserted and removed. In the past, this type of box was used for sending small items like jewelry or CDs. However, since the rise in popularity of e-commerce, this type of box has become popular for sending larger items like shoes or clothing.HOT PRODUCTS.