There are two additional certified mail services available with Certified Mail: Return Receipt service and Restricted Delivery. Both are available for an additional fee when used with Certified Mail.
Return Receipt service provides you with a copy of the signature that's collected when USPS delivers the certified mail. You can use regular return receipt, which means the signature will be returned via a green card in the mail. You can also opt for Electronic Return Receipt, which means you will get a PDF copy of the signature collected on a piece of electronic equipment the carriers use when delivering mail.