Which of the following is NOT an extra service that can be added to Express Mail?

Express Mail, now known as Priority Mail Express, is a premium service offered by USPS that provides expedited shipping options with guaranteed delivery times. When considering additional services that can enhance or complement Express Mail, options such as COD (Collect on Delivery), Return Receipt, and Additional Insurance are all valid add-on services.

COD allows the postal service to collect payment upon delivery, which is useful for businesses or individuals sending items that require a payment upon receipt. Return Receipt provides the sender with proof of delivery, confirming that the item was delivered and providing the recipient's signature as evidence. Additional Insurance allows senders to insure higher-value items against loss or damage during transit, giving extra peace of mind for valuable shipments.

In contrast, the Media Mail Rate is a specific mail class designed for shipping educational materials and certain types of media at a lower cost. It is not compatible with Express Mail services, as it does not offer the expedited delivery and high-priority features associated with Express Mail. Thus, Media Mail Rate cannot be added on as an extra service for Express Mail shipments.