Registered mail is a mail service offered by postal services in many countries which allows the sender proof of mailing via a mailing 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;
• 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 specified person, or authorized agent, will receive the specific mail.

The name of this service varies from country to country, and postal services in some countries offer more than one level of service under different names (e.g., "certified mail" and "registered mail" in the U.S.). See the country-specific information below for details.