USPS Signature Confirmation Label API
The U.S. Postal Service provides a suite of USPS Web Tools that customers may integrate into their own websites to validate or find mailing addresses, track and confirm mail delivery, calculate shipping rates, and create domestic or international shipping labels.
With this service, senders can create a signature confirmation label and an online customer record for a parcel shipped within the U.S., allowing the sender or sender's customers to track delivery status of that parcel.
