What determines the processing category of a mailpiece?

The processing category of a mailpiece is primarily determined by its physical dimensions and characteristics. This includes factors such as the size, shape, weight, and format of the mailpiece. Each of these characteristics influences how the item is handled through the mail system, which is designed to operate efficiently based on standardized criteria.

For example, larger or unusually shaped mailpieces may require different handling than standard letter-sized items. The physical properties dictate how the mailpiece can be processed through automated sorting systems, which are calibrated to manage specific dimensions and weights. As a result, understanding these physical attributes is essential for determining the most appropriate processing category for any mailpiece.