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HELP CENTER · FAQDomains1 min read

How do MX priority values affect mail delivery?

MX records list mail exchangers for a domain, and the preference value helps sending systems choose among them. Lower numeric preference values are generally tried first, but actual retry and failover behavior depends on the sending system and whether the target is reachable.

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Order the intended mail exchangers

Publish the correct hostnames and preference values for primary and fallback services, confirming each target has the required address records. A preference value does not guarantee that the sender will use a backup in every failure scenario.

Avoid pointing an MX record to an alias when the relevant DNS rules prohibit it. Check the mail provider’s setup instructions and validate the final answers from authoritative DNS before changing live mail flow.

Test and monitor delivery

Query the MX set and verify every target resolves and accepts mail as intended. During a migration, keep old and new mail routing coordinated so messages are not split unpredictably between systems.

Watch delivery reports and queue behavior after a change. If mail is rejected or delayed, inspect the sending system’s diagnostic response and recipient-side logs rather than assuming priority alone caused the outcome.

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