MX record

A mail exchanger record (MX record) is a type of resource record in the Domain Name System that specifies a mail server responsible for accepting email messages on behalf of a recipient's domain, and a preference value used to prioritize mail delivery if multiple mail servers are available. The set of MX records of a domain name specifies how email should be routed with the Simple Mail Transfer Protocol (SMTP).

Overview

Resource records are the basic information element of the Domain Name System (DNS). They are distinguished by a type identification (A, MX, NS, etc.) and a DNS class (Internet, CHAOS, etc.). The records have a validity period (time-to-live) assigned to them, indicating when the information they hold must be refreshed from an authoritative name server. Resource records are organized within the DNS based on their name field, which is a fully qualified domain name (FQDN) of a node in the DNS tree. In the case of an MX record, this specifies the domain name of a mail recipient's email address, i.e. the portion after the @ symbol that delimits the recipient's account name.