The United States Post Office offers a certified mail option for consumers who need to send important documents and have proof that the mailing reached its destination. The sender can access delivery information online, and the Post Office will keep a copy of the signature obtained at delivery on file. Certified mail cannot be sent internationally.

First-Class Mail

Certified first-class mail can be sent in an envelope or small package, and cannot weigh more than 13 ounces. Most business correspondence, bills and letters are sent by first-class mail and can be sent certified mail for an additional fee. This service typically provides delivery within three business days to most areas in the continental United States.

Priority Mail

Consumers should select the priority mail option for their certified mail if the article needs to arrive at its destination within two to three days. Priority mail costs more, but is an expedited service that is recommended for certified mail during high-volume mail times, such as Christmas.

Extra Services

Extra services such as return receipt and restricted delivery can be added to certified mail for an additional fee. Return receipt provides the sender with a post card or electronic copy of the recipient's signature and can be purchased before or after mailing. Restricted delivery allows only a specific person or his authorized agent to take delivery of the certified mail.