If a customer needs a return receipt for international mailing, which service should they use?

The appropriate service for obtaining a return receipt for international mailing is Registered Mail. This service offers additional security and tracking features, which is particularly important when sending valuable items abroad.

When a customer uses Registered Mail, they receive a return receipt that confirms delivery and provides a physical signature from the recipient. This feature is crucial for international shipments where proof of delivery may be needed for both the sender and receiver. While other mailing options like Priority Mail and Express Mail may also offer tracking or delivery confirmation, they do not have the same level of security and formal record-keeping that Registered Mail provides, particularly for international services.

First-Class Mail, while affordable for sending letters and lightweight packages, does not provide the return receipt option for international shipments. Therefore, for international mailing where a return receipt is essential, Registered Mail is the correct choice as it combines security and acknowledgment of delivery effectively.