MX Record Lookup

Check MX records (mail servers) for any domain across 12 global resolvers. Free real-time DNS propagation checker.

What is an MX record?

An MX record ("mail exchange") tells the world which servers accept email for a domain. Each MX record has a priority (a number) and a host. Lower numbers are tried first; higher numbers are backups. Sending mail servers look up MX, sort by priority, and try each host in order.

When to check MX records

• You just switched email providers (Google Workspace, Microsoft 365, Fastmail, etc.) and need to confirm the new MX is live everywhere
• Email is bouncing and you suspect the MX is misconfigured or stale
• You're hunting down a "spoofed sender": verify the legitimate MX hosts
• You want to confirm a domain is using a particular mail provider

Reading the results

Each MX value has the form priority hostname (for example, 10 alt1.gmail-smtp-in.l.google.com). Lower priority numbers are preferred. Multiple records at the same priority are randomly load-balanced. Sending mail servers try lowest priority first and fall back through the list if the preferred host is unreachable.

Common errors and pitfalls

• Mail bouncing after a provider switch: old MX records may still be cached. Lower the TTL before the switch, or expect up to TTL-duration of bouncing during the cutover.
• MX record points at an IP: invalid. MX targets must be hostnames. Many receiving servers will reject mail to a domain with malformed MX.
• Conflicting MX from old provider: when migrating to a new email host, make sure to remove the old MX records, not just add new ones. Keeping both means random delivery to the wrong server.
• "Null MX": a single record 0 . means "this domain accepts no mail." Often set on parked domains. If you see this on a domain that should accept mail, the MX is misconfigured.
• MX exists but mail still bounces: check SPF, DKIM, and DMARC at the receiving end too. Modern receivers reject mail that fails authentication, regardless of MX.

FAQ

What does the priority number mean?

Lower priority is preferred. 10 mail.example.com is tried before 20 backup.example.com. Equal priorities are load-balanced.

Can MX records point to an IP address?

No. MX records must point to a hostname (which then resolves via A or AAAA records). Pointing MX directly at an IP is a spec violation many mail servers will reject.

What does an empty MX result mean?

The domain doesn't accept email at that name. Some providers use a "null MX" (a single record with priority 0 pointing to .) to explicitly signal "no mail here."

How many MX records should I have?

Most providers give you 3–5 by default for redundancy. Two is fine for low-volume domains. Equal priorities provide load balancing; tiered priorities provide failover.

Should the MX hostname have its own A record?

Yes. The MX target must resolve to A or AAAA. Pointing MX at a hostname that doesn't resolve is the same as pointing MX at nothing.

Background reading

For the full email-authentication picture, also see SPF, DKIM, and DMARC. The DNS Records Explained guide ties it all together.