How to Check an MX Record

To check an MX record properly, query MX for the exact domain that should receive mail. That gives you the published preference values and target hostnames that receiving systems are expected to use.

If there are no MX records where you expect them, inbound mail routing may be broken or at least unclear.

• MX Lookup

An MX record is not just a hostname. It is a priority plus a target. Lower numbers are preferred first, so a technically valid set of MX records can still be wrong if the priorities send mail to the wrong platform.

0 example-com.mail.protection.outlook.com

That target should look realistic for the provider in use. For example, Microsoft 365 normally uses a tenant-specific mail.protection.outlook.com hostname, while Google Workspace may use smtp.google.com or a valid legacy aspmx layout.

The next question is whether the MX target belongs to the provider you actually expect to be receiving mail. Migrations often leave old MX values in place or mix providers accidentally.

• Email Provider Setup Checker
• How to tell which email provider a domain uses

The MX value itself is a hostname, so you should also confirm that hostname resolves correctly. If the target hostname is broken, mail can fail even though the MX record exists.

It is also helpful to compare the authoritative answer with what public resolvers return. That separates a real MX misconfiguration from a short-lived cache or propagation issue.

• Checking the wrong domain or subdomain
• Looking only at the target hostname and ignoring priority values
• Assuming any familiar provider hostname is correct without checking the exact tenant or routing design
• Mistaking cached public resolver answers for the current authoritative answer

• Query the domain's MX records
• Review the number of MX records and their priorities
• Check whether the targets look like the intended mail provider
• Resolve the MX target hostnames if needed
• Compare authoritative and public resolver answers if the result looks inconsistent
• If the setup looks mixed, compare it with provider-specific expectations

If you want to validate this topic in practice, these DNS Pro tools are the fastest next step.

• MX Lookup
• Email Provider Setup Checker
• Email Security Check