MX Record Checker
Queries a public record from our server — not your files.
Look up where a domain's mail is delivered, and check that the answer actually works. Reading the MX records is the easy half; the half that finds real faults is resolving each mail host afterwards, because an MX pointing at a name with no address record is a domain that accepts no mail while looking perfectly configured. Both take a resolver, so the domain you enter is sent to our server, which queries public DNS. Public records only — never a file from your machine.
This tool is an exception on this site. Everything else here runs entirely in your browser, but a web page cannot query DNS, read a certificate or see another site’s response headers — so the name or URL you enter is sent to our server, which looks up the public record and sends the answer back. The answer is cached for up to a minute. No file of yours is read, uploaded or stored, and there is no account.
How to use MX Checker
- 1
Enter the domain that receives the mail — the part after the @.
- 2
Read the mail exchangers in preference order, lowest number first.
- 3
Check each host resolved to an address; one that did not is where mail is being lost.
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Frequently asked questions
Does this send my data anywhere?+
The domain name goes to our server, which queries public DNS for its MX records and then for the address of each mail host named in them. MX records exist to be read by every sending mail server on the internet. Nothing is uploaded from your device.
What does the preference number mean?+
Lower is tried first. A sender attempts the lowest-numbered host, and moves to the next only if it cannot connect. It is a priority, not a weight — 10 and 20 behave identically to 1 and 2. Equal numbers mean senders pick between them at random, which is how simple load balancing is done.
We have no MX record and mail still arrives.+
RFC 5321 says a sender with no MX to work with falls back to the domain's A record, so mail is being delivered to whatever is on your web server's address. That is almost never intended, and it stops the moment you move hosting. Publish an MX.
What is a null MX?+
A single record reading "0 ." It states that the domain accepts no mail at all, so senders reject immediately instead of retrying for days. It is the right configuration for a domain used only for sending, or for one you own and do not use — and much better than silence, which makes every spammer's bounce your problem.
Does an MX record control who can send as my domain?+
No. MX is delivery only — where mail TO you goes. Who may send AS you is SPF, DKIM and DMARC, each published separately. Domains get spoofed all the time with perfectly correct MX records.