A delivery service offered by the United States Postal Service that is often used to send legal notices to addresses within the United States. Upon the payment of a fee, the sender is given a receipt when an item is mailed and a record of the delivery is kept by the addressee’s local post office. For an additional fee, the sender may have the addressee sign another receipt when the item is delivered, and that receipt is returned to the sender, in which case the service is known as “certified mail, return receipt requested.” Some court rules provide that service by certified mail is acceptable.