Which of the following is NOT a class of Package Services?

First-Class Mail is not classified as a Package Service; rather, it is considered a distinct category of mail service offered by the postal system. Package Services typically include Media Mail, Bound Printed Matter, and Library Mail, which are designed for specific types of shipments with varying rates based on the content type and weight.

Media Mail is specifically for shipping educational materials, while Bound Printed Matter allows for the shipping of certain printed materials in bulk. Library Mail provides reduced rates for items sent to and from libraries. In contrast, First-Class Mail encompasses a broader range of personal correspondence and parcels, typically providing faster delivery and more extensive service features, but it does not fit the criteria for Package Services. Understanding these classifications is crucial for effectively identifying and utilizing the appropriate mailing services.