MX Record
Specifies the mail servers responsible for accepting email for a domain. Priority values determine delivery order when multiple servers are configured.
Mail Exchanger Record
When another mail server sends email to user@example.com, it looks up the MX records for example.com to find where to deliver the message. The MX record points to a mail server hostname, and the sending server then resolves that hostname to an IP address.
The priority value (a lower number = higher priority) determines which server to try first. Multiple MX records create redundancy: if the primary mail server is unreachable, the sending server retries with the next-lowest-priority server. Equal-priority MX records enable load balancing.
- MX target must be a hostname — never an IP address or CNAME (RFC 2181)
- The target hostname must have its own A/AAAA record (a "glue" requirement)
- Lower priority number = higher preference (10 is preferred over 20)
- Equal priority values = load balanced; sending servers choose randomly
- No MX record = sending servers fall back to the A record (not recommended)
- MX records must be at the zone apex for a domain to receive email
MX Records and Email Authentication
MX records work alongside SPF, DKIM, and DMARC records to authenticate inbound and outbound email. While MX records define where to deliver email for your domain, SPF defines which servers are authorized to send on your behalf.
The mail server hostname in your MX record should also have a matching PTR (reverse DNS) record. Many spam filters reject or score negatively mail from servers where the sending IP's PTR record doesn't match the server's hostname. This is configured at your IP hosting provider or ISP, not in your domain's DNS.