Which of the following is NOT a class of mail?

The option identified as Economy Mail is accurately noted as not being an official class of mail recognized by the United States Postal Service (USPS) or typical mail classification systems. The classifications of mail include First-Class, which encompasses standard letters, postcards, and priority items; Package Services, which covers a variety of shipping options for parcels; and Periodicals, which refers to publications such as magazines and newspapers that are published regularly.

While the concept of "Economy" suggests a lower-cost option, it does not correspond to a specific class of mail but might represent a service level or pricing structure within existing mail categories. Understanding the recognized classes of mail is crucial for anyone involved in postal services, as it dictates how various types of mail are handled, priced, and delivered.