MX lookup

Use this MX lookup to inspect mail server priorities, IP addresses, provider hints and forward-confirmed reverse DNS. Review routing findings and a bounded public SpamCop check.

Free, no account. Thirty lookups per hour.

You can paste an email address; only the part after the @ is used. An answer is reused for two minutes.

An MX lookup lists the mail servers that accept email for a domain. Senders try the lowest priority number first. This lookup also finds each server’s IPv4 and IPv6 addresses, names the provider when the hosts match a known one, and explains a null MX or a domain that has no MX record at all.

How to use this tool

Enter the domain
Use the part after the @ in an email address, such as example.com. A full email address or a URL also works; we keep only the domain.
Read the priority
Senders try the server with the lowest number first and move to the next one when it does not answer. Servers with the same number share the mail between them.
Check each server’s addresses
Every MX host needs its own A or AAAA record. The mail standards ask for a plain hostname there, so a CNAME, an IP address typed into the record or a private address is flagged.
Null MX and the fallback
A single MX record of "." with priority 0 is a null MX (RFC 7505): the domain says it never receives mail. With no MX record at all, senders try the domain’s own A or AAAA address instead (RFC 5321).

Questions before you start

It is the order of preference, and lower numbers are tried first. A backup server usually has a higher number, such as 20 when the main one has 10. Only the order counts: 10 and 20 work the same as 10 and 11.

Sometimes. Senders then try the domain’s A or AAAA address, as RFC 5321 describes, but mail only arrives if a mail server listens there. Most web hosting does not, so add the MX records your email provider gives you.

An MX record that points to "." with priority 0, defined in RFC 7505. It tells senders the domain accepts no email, so they reject a message at once instead of retrying for days. It suits domains that only run a website.

MX records only tell other servers where to send mail for your domain. Whether the mail you send reaches the inbox depends on SPF, DKIM and DMARC records and on your sending reputation.

From the MX hostnames, for example aspmx.l.google.com for Google Workspace or mail.protection.outlook.com for Microsoft 365. We match a short list of well known providers. When no provider is named, nothing is wrong; it is simply not on our list.

Related tools

  • SPF record checker

    Use this SPF record checker to expand includes and inspect candidate IP ranges. Add your public sending IP to trace mechanism order, macros and the DNS lookup limits.

  • DMARC checker

    Use this DMARC checker to read policy and reporting permissions, probe DKIM keys and inspect BIMI, MTA-STS and TLS-RPT. Add your actual selector for a precise key check.

  • Email blacklist checker

    Use this email blacklist checker to test your mail servers or one IPv4 address against DNS blocklists whose terms allow it. See which lists were skipped and how to get removed.

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