MX record
What is MX record?
An MX (Mail Exchange) record is the DNS entry that tells any sending mail server which server is responsible for receiving email on behalf of a domain, including a priority order when multiple mail servers are listed as backups. Without a correctly configured MX record, incoming mail addressed to a domain has nowhere to be delivered, regardless of how well SPF, DKIM, and DMARC are configured for outgoing mail from that same domain.
More detail
A domain can list multiple MX records with different priority values, so mail is attempted against the highest-priority server first and falls back to a lower-priority one if the primary is unreachable.
MX records govern inbound mail delivery specifically — they're a separate concern from SPF, DKIM, and DMARC, which govern how outbound mail from that domain is authenticated.
Frequently asked
- What happens if a domain's MX record is missing or misconfigured?
- Incoming mail addressed to that domain has no valid destination server to deliver to and will bounce, regardless of how well the domain's outbound authentication (SPF, DKIM, DMARC) is set up, since MX records govern inbound delivery specifically.
- Why would a domain have more than one MX record?
- Multiple MX records with different priority values provide redundancy — mail is delivered to the highest-priority server first, falling back automatically to a lower-priority backup server if the primary is temporarily unreachable.
See also
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