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MX Validator

Check email deliverability for any domain.

MX records tell the internet where to deliver email for a domain. Without valid MX records, a domain cannot receive any email — messages bounce back to the sender.

SPF (Sender Policy Framework) is a TXT record that lists which mail servers are authorized to send email on behalf of your domain. It prevents spoofing and helps your emails pass spam filters.

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing emails. Receivers verify the signature by looking up a public key in DNS, ensuring the email wasn't tampered with in transit.

DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together with a policy — none (monitor only), quarantine (spam folder), or reject (bounce). It tells receivers what to do when authentication fails.

This tool checks all four — MX, SPF, DKIM, and DMARC — so you can quickly see if a domain is properly configured for sending and receiving email.

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Next step

Mail broken after a DNS change?

Missing MX, SPF, DKIM, or DMARC is why messages bounce after a host move. You can fix the records in your DNS panel, or route mail through Cloudflare Email Routing.

Common questions

It looks up the MX (Mail Exchange) records for a domain to verify that email can be received and identifies the mail servers responsible.

If no MX records exist, email delivery will fall back to the domain A record. For reliable email, always configure proper MX records pointing to your mail server.

Yes. Enter any domain name and the tool will query its MX records and display priority and mail server details.

What the MX validator checks

Mail Exchange (MX) records tell the internet where to deliver email for your domain. This tool looks up MX hosts and priorities, checks that those hosts resolve, and inspects related authentication signals in DNS — especially SPF in TXT records — so you can see whether mail routing and basic anti-spoofing are intact.

Broken MX is one of the most common “website looks fine, business is on fire” failures: the homepage still loads while invoices, password resets, and customer mail bounce. Validating MX after every DNS edit should be muscle memory.

When to validate MX records

  • Before cutting over to Google Workspace, Microsoft 365, or a new transactional ESP
  • Immediately after any A/AAAA or nameserver change (migrations often update web only)
  • When mail arrives to some providers but not others, or bounces with “cannot find mail server”
  • After buying or transferring a domain — leftover MX from the previous owner is a real risk
  • As a routine check inside the Website Health Check

How to read the results

MX list and priority — lower preference numbers are tried first. Multiple MX values are normal for backup MTAs; a single MX is fine for small setups.

Host resolution — each MX hostname must resolve to usable addresses. An MX pointing at a CNAME or at a host that does not exist will fail delivery unpredictably.

SPF / auth context — if you send mail as this domain, SPF should authorize your real senders without exceeding the 10-DNS-lookup limit. DMARC and DKIM complete the picture; use DNS Lookup for TXT deep-dives and our SPF, DKIM & DMARC guide.

Common problems

  • Web DNS updated; MX still on the old shared host
  • MX hostname is a CNAME (discouraged / often broken depending on provider)
  • SPF include: chains that exceed 10 lookups → permerror
  • No DMARC while marketing tools send as your domain
  • TTL still caching old MX at major providers hours after you “fixed” it — confirm with DNS Propagation

Example scenario

A retailer moved the website to a new host on Friday. Monday, password-reset mail vanished. MX still pointed at the previous host’s mail exchanger, which had already been decommissioned. Restoring MX to Microsoft 365 and waiting for TTL cleared the backlog. The playbook for this pattern lives in Fix Email After a DNS Migration.

Limitations

We validate public DNS configuration and basic resolvability — we do not send test messages, open SMTP sessions against your servers, or prove inbox placement. Greylisting, reputation, and content filters are out of scope. Always confirm with your mail provider’s admin console after DNS changes.

Related resources

Fix Email After DNS Migration · SPF, DKIM & DMARC · DNS Lookup · DNS Propagation · Website Health Check