Certified mail is a service provided by the United States Postal Service in which the sender of an envelope or package receives a proof of delivery postcard after the item has been delivered, signed by the recipient. The postcard includes the date and time. The sender then knows the item has been received by the addressee.
The USPS maintains a record of certified mail delivery, which the sender can track through the USPS website using a unique code.
The certified mail service can only be used with first class or priority mail. As of 2009, certified mail cost $2.70.
If a carrier attempts to deliver certified mail when the addressee is not home, the carrier leaves a notification slip to pick up the item at the post office or to call the office for re-delivery.
Legal documents are commonly sent by certified mail, and the Internal Revenue Service uses certified mail to send overdue notices.
The signature on certified mail confirms the item has been received by the addressee and not only delivered to the address, as denoted by the less expensive and more frequently-used USPS service called delivery confirmation.