MX records: the signpost for inbound mail.

Updated August 2026 · 6 min read

An MX record tells sending mail systems which host accepts mail for a domain. It does not authenticate your messages or create a mailbox.

Priority is a preference

Lower numbers have higher priority. Multiple records can provide failover, but only use a secondary if it is deliberately configured to receive or queue mail. A backup that rejects mail is not a backup.

Common mistakes

• Pointing MX to an IP address instead of a hostname.
• Leaving an old provider’s MX record during a migration.
• Forgetting that the MX hostname itself needs an A or AAAA answer.
• Assuming an MX change also updates SPF, DKIM or DMARC.

Before you edit

Write down every existing MX value and priority. Confirm the new provider’s exact hostnames and verify them with the DNS lookup tool. Plan an overlap and monitor test messages from more than one sender.

Then read SPF, DKIM and DMARC for outbound trust.