Certified mail is a service offered by the U.S. Postal Service (USPS) that allows you to verify a letter or package you sent has been delivered and received. Certified mail can only be sent to locations in the United States and its territories, and to APO/FPO addresses. As of 2009, certified mail service costs $2.80.
When you purchase certified mail service, you receive a date-stamped receipt, along with a tracking number you can use to verify delivery.
Confirmation of Receipt
Unlike delivery confirmation, certified mail verifies the package was received. The postal carrier obtains a signature from someone at the specified address at the time of delivery.
People often choose certified mail when sending legal documents or items for which the date of arrival is essential.
Restricted Delivery Option
Certified mail can include restricted delivery service if you want to confirm a specific person receives the package and signs for it.
Return Receipt Option
Another special service available is return receipt, which provides a return postcard with the recipient's signature or an e-mail attachment with an image of the signature.