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MX record checker

Enter a domain to see its mail exchanger (MX) records, sorted by priority and resolved to their IP addresses, with any problems flagged — no MX, a Null MX, or a host that doesn't resolve. The lookup runs in your browser over DNS-over-HTTPS.

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MX records

Priority	Mail exchanger	Resolves to

MX checker FAQ

What does the MX checker do?+

It looks up a domain's MX (mail exchanger) records over DNS-over-HTTPS, sorts them by priority, and resolves each MX host to its IP address. It flags common problems: no MX at all, a Null MX (the domain refuses mail), or an MX hostname that doesn't resolve.

What is MX priority?+

Each MX record has a priority number; lower numbers are preferred. Sending servers try the lowest-priority MX first and fall back to higher numbers if it's unreachable. Having more than one MX gives you redundancy, though many domains run a single MX behind a resilient provider.

What is a Null MX?+

A Null MX (a single MX record of priority 0 pointing to '.') is defined by RFC 7505 to say a domain sends but never receives mail. If you see it, the domain is explicitly declining all inbound mail — useful on send-only or parked domains.

Why would an MX host not resolve?+

If an MX hostname has no A/AAAA record, mail servers can't connect to it and delivery fails. It usually means a typo in the MX record or a removed host. Every MX hostname must resolve to a reachable IP.