Free MX Checker: Spot False Redundancy

Check your MX records

Enter a domain below. The checker reads the live MX records at the domain apex over encrypted DNS and tells you which mail exchangers receive your mail, in what order, and whether the primary one actually resolves.

Records look wrong? Have a specialist double-check them — the $49 Email Domain Trust Audit is a fixed-output report with risk notes and prioritized next steps.

What the checker looks for

MX records at the domain apex (for example example.com) — mail routing lives at the root, not on a subdomain.
Priority order — the lowest number is the primary; the checker lists them in the order senders try them.
The RFC 7505 null MX — a lone 0 . means "no mail here," which is correct for non-mail domains and broken when mixed with real records.
Primary host resolution — the checker verifies the top-priority exchanger resolves to an A or AAAA record, because a pointer to a dead host is a silent mail black hole.

No MX records?

Without explicit MX records, senders fall back to the apex A record — delivery "works" until a firewall rule or IP change silently kills it. Point proper MX records at your mail provider (Google Workspace, Microsoft 365, or your host), wait for DNS to propagate (minutes to hours), and re-run the checker.

Routing is only the first leg — authentication decides whether the mail that arrives is trusted. Run the Free Email Domain Trust Checker to see where your domain stands on SPF, DKIM, and DMARC.

Verify the rest of the set

MX is the routing leg. Verify the authentication set, free, in your browser:

Prefer done-for-you?

If you'd rather hand this to a specialist, submit your domain for the Email Domain Trust Audit — a fixed-output report with risk notes and prioritized next steps. When records are broken and you want them fixed, the 99 Mailbox Rescue gets them fixed within 48 hours, zero tech touch.

Frequently asked questions

What does the MX checker look up? The checker queries the live MX records at the domain apex over DNS (via encrypted DNS-over-HTTPS), then lists each mail exchanger with its priority number. It flags duplicate priorities, RFC 7505 null-MX records, and verifies that the primary mail host resolves to an A or AAAA record.

What do the priority numbers mean? Lower numbers are tried first — priority 10 is the primary mail server, 20 is the first backup, and so on. Hosts that share a priority are picked at random, which gives you load-sharing rather than strict failover.

No MX records found — does mail still work? Technically yes: senders fall back to the apex A record of the domain (implicit MX). It is fragile — the web server and the mail server share an IP, so one firewall rule can silently kill inbound mail. Publish explicit MX records pointing at your mail provider.

What is a null MX record? A single MX record of "0 ." (RFC 7505) tells senders the domain accepts no mail. It is the correct setup for domains that never receive mail. It must stand alone — mixing it with real MX records creates undefined sender behavior.

My MX records exist but mail bounces — what next? The MX records point senders at the right host, so the problem is downstream: the mail host does not resolve, port 25 is blocked, or the provider rejects the sender. The Email Domain Trust Audit checks the full chain — records, host reachability, and authentication.

Where Does Your Domain's Mail Actually Go?