Free tool
MX record lookup
See which mail servers receive email for a domain, in priority order - and whether the records are set up the way sending servers expect.
In short
MX records tell other mail servers where to deliver email for a domain. Each record names a mail server hostname and a priority; senders try the lowest number first and fall back to the others if it does not answer.yourdomain.com. MX 1 smtp.google.com.
What correct MX records look like
That records exist. A domain with no MX records falls back to its A record for incoming mail, which usually is not a mail server - so mail to it bounces or waits in queues for days. A domain that should never receive mail can say so with a null MX, a single record with priority 0 and a target of a lone dot (RFC 7505).
That each record points at a hostname. An MX target must be a hostname with its own A or AAAA record. RFC 5321 does not allow an IP address, and pointing MX at a CNAME breaks delivery at some senders.
Priorities that make sense. Lower numbers are tried first. Records with equal priority share the load. A backup server with a higher number only helps if it can actually deliver onward to the primary.
MX records and sending email
MX records control receiving, not sending - SPF, DKIM and DMARC decide whether mail you send is trusted. They matter for senders too, though: bounces and replies go to the domains in your Return-Path and Reply-To, and some receivers distrust a sending domain that cannot receive mail at all.
How the three authentication records work together is explained in SPF, DKIM and DMARC explained.
Questions
How do I check a domain's MX records?
Enter the domain above. The lookup reads its MX records from public DNS and lists each mail server with its priority, lowest first, and warns when the domain has none.
What does MX priority mean?
Senders try the MX record with the lowest priority number first. Records with the same number share the load, and higher numbers are fallbacks.
Can an MX record point to an IP address?
No. An MX record must point at a hostname that has its own A or AAAA record. Publish the IP on a hostname such as mail.yourdomain.com and point MX at that.
What is a null MX record?
A single MX record with priority 0 and a target of "." (RFC 7505). It tells senders the domain accepts no mail, so they bounce immediately instead of retrying.
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