It’s important to know which service to use if you need documentation for an important letter or parcel. The terms “registered” and “certified” are often used interchangeably, but are actually for very different services.
Certified mail provides a mailing receipt, a trackable number and proof of receipt. It is often used for legal documents and other mail items requiring provable delivery by a specific date.
For a higher fee, registered mail provides the services of certified mail and additional protection for items that are irreplaceable or have monetary value. Registered mail may currently be insured for up to $25,000. A well-known example of when registered mail was selected was when the Hope diamond was shipped to the Smithsonian Institution in 1958 and was insured for $1 million (http://postalmuseumblog.si.edu/2012/11/delivering-the-hope-diamond.html
By adding a USPS return receipt (the PS Form 3811 “green card”) to either a certified or registered mail piece, the sender will receive the card back in the mail after delivery, with a hand-written signature and date of delivery.
For more information or questions regarding mail services, please contact the Division of Mail Management Services at (301) 496-3586.