MX Lookup

An MX record names a server that accepts mail for a domain, with a preference number. Senders try the lowest number first and fall back to higher ones only when it cannot be reached. This looks up a domain's MX records through Cloudflare's DNS-over-HTTPS resolver from Quietlytic's backend and lists them in the order a sender would use them.

Three answers that are easy to misread

A single MX of 0 . is a null MX (RFC 7505): the domain says it accepts no mail at all. No MX at all is different — senders then fall back to the domain's own A or AAAA address, so mail can still arrive somewhere, often at a web server. And an MX pointing at an IP address instead of a host name is invalid under RFC 5321, which many senders handle badly. Each is called out when it appears.

SPF and DMARC beside the MX records

Receiving mail is half of a domain's mail setup. The same lookup reads the domain's SPF record and the DMARC record at _dmarc, and reports whether each exists and what it enforces. For the full analysis of either, use the SPF Checker or the DMARC Checker; for other record types, the DNS Lookup.

Why this tool needs a bot check

It queries a resolver on your behalf, which is cheap per lookup but easy to script at volume. One Turnstile solve unlocks lookups for 30 minutes in this tab, shared with the DNS and email-authentication tools, and lookups are limited per IP address per hour.

Look up a domain hosted on a large mail provider and several MX hosts appear, often with the same preference so the load is shared. A parked domain that should never receive mail is best served by a null MX, and is listed with a note saying so rather than as an error. A URL or email address pasted in is trimmed to its domain.