Which of the following categories is NOT included in the five processing categories?

The category of heavy parcels is not included in the five processing categories recognized by the USPS. The USPS categorizes mail processing into specific groups to streamline sorting and handling effectively.

The five primary processing categories typically include letters, flats (which are larger than letters but not too bulky or heavy), and irregular parcels. Irregular parcels can encompass items that do not fit neatly into the standard mail classifications.

Heavy parcels, while they are a type of mail, do not fall under the established categories for mail processing as they are processed differently due to their size and weight, thus being excluded from this list. This categorization helps ensure that each type of mail is handled appropriately based on its characteristics, ultimately supporting efficient postal operations.