Registered mail is a postal service in many countries which allows the sender proof of mailing via a receipt and, upon request, electronic verification that an article was delivered or that a delivery attempt was made. Depending on the country, additional services may also be available, such as:

• a chain of custody, where the posted item has its details recorded in a register to enable its location to be tracked, sometimes with added insurance to cover loss;
• a return receipt, called an avis de réception, which provides a postcard or electronic notification with the date of delivery and recipient signature;
• restricted delivery, which confirms that only a specific person or authorized agent will receive the mail, and;
• certified mail, in the United States.