MX Record Lookup
Look up the mail servers (MX records) for any domain — sorted by priority.
Quick answer: MX Record Lookup: look up the mail servers (MX records) for any domain — sorted by priority. Runs on our servers, files deleted within minutes, free, no signup.
Last updated
Good to know
MX records are the signposts that tell the world where your mail lives. Each record pairs a hostname with a preference number, and senders always attempt the lowest number first. A common misconception is that a lower priority means "less important" — it is the opposite: priority 10 is tried before priority 20. Many providers publish several records at the same preference so incoming mail spreads across redundant servers.
When you are debugging a bounce, the first thing to confirm is that the MX host actually resolves to an A/AAAA record and answers on port 25. An MX pointing at a CNAME is technically invalid per RFC 5321, even though some resolvers tolerate it, so watch for that. A domain with no MX record at all falls back to its A record — which is rarely what a serious mail setup intends.
Reading the MX list is only half the deliverability picture. Once you know which hosts receive the mail, verify that those same hosts are authorized to send it by checking your SPF, DKIM, and DMARC alignment with the email authentication checker. Together, MX plus authentication records explain almost every "why did this message vanish?" question.
Frequently asked questions
- What are MX records and why do they matter?
- MX (Mail Exchanger) records tell sending mail servers which host accepts mail for a domain. If they're missing or wrong, no email gets through.
- Why does this run on a server?
- Browsers can't make DNS queries directly — DNS uses UDP, which JavaScript has no API for. Our server makes the query in milliseconds and forwards the result.
- What does priority mean?
- Lower numbers are tried first. If multiple MX records share a priority, mail servers load-balance between them.
- Will you query private domains?
- We refuse private (RFC1918) IPs and intranet TLDs to avoid being used as a probe inside corporate networks. Public domains only.
- Is there a rate limit?
- Yes — about 60 lookups per minute per IP. Email us if your team needs a higher allowance.