What is a coffin bin typically used for?

A coffin bin is specifically designed to accommodate flat volume mail. These bins have a larger surface area and depth to effectively hold various types of flat mail items, which can include oversized letters, magazines, catalogs, and other flat-shaped materials. Their design allows for easy stacking and efficient handling, making them well-suited for transporting bulk flat mail through the postal system.

In contrast, storing oversized packages typically requires containers or bins designed to handle larger dimensions, which are not the primary function of a coffin bin. Sorting letter-sized mail is typically done using different sorting equipment that caters specifically to the smaller format of letters. Transporting perishable items demands specialized bins with temperature control, which coffin bins do not provide. Thus, the coffin bin's primary use for flat volume mail stands out as the most relevant option in this context.