MX priority

MX priority is the preference number attached to an MX record. It helps sending mail systems choose which mail server to try first when a domain lists more than one.

Does a larger number mean higher priority?

No. The lower number is preferred. If example.com lists 10 mail-a.example.net and 20 mail-b.example.net, a sending system normally tries the server with preference 10 first. The server with 20 is an alternate if the first choice cannot accept the message, depending on how the sending system is set up to retry delivery.

The number does not measure server quality, capacity, or importance in everyday terms. It is a routing preference. Servers with the same preference can be used in either order or have traffic shared according to sender behavior; do not assume that the records alone provide a complete backup service. Each destination must be configured to handle the domain's mail.

Related terms

• MX record — contains the preference and destination
• Mail server — the host that accepts or relays messages
• DNS — publishes MX records