What key feature does return receipt requested service offer?

Return receipt requested service is designed to provide proof that a piece of mail has been delivered and that it has been received by the intended recipient. This service is particularly important for senders who need to verify the delivery, such as in legal or business communications. When a sender opts for this service, they receive a signed delivery confirmation card upon delivery, which indicates the recipient's signature and the date of receipt. This card serves as an official document verifying that the item has been received, making it a critical feature for important or sensitive correspondence.

In contrast, other options do not capture the essence of what return receipt requested service offers. While expedited shipping might expedite the delivery process, it does not provide confirmation of receipt. Similarly, while having a tracking number allows senders to monitor the package's journey, it does not confirm that the item was received by the recipient. Lastly, although insurance can protect the sender against loss or damage, it does not relate to receipt verification, which is the primary purpose of the return receipt service.