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MX Lookup

An MX lookup lists a domain's mail servers in priority order and resolves each host to A and AAAA addresses.

This check runs on our server. The address you enter is used only for this check and is not stored.
Updated

This check runs on our server. The address you enter is used only for this check and is not stored.

How to use the MX Lookup

  1. Enter the domain that should receive mail.
  2. Choose a resolver.
  3. Tick the robot check and press Look up.
  4. The lowest priority number is tried first. Equal numbers can be used together.

How it works

This check runs on our server. The domain is not stored.

The MX query returns a preference and a hostname. Preference 10 is used before preference 20. After that list arrives, the tool looks up A and AAAA for each mail host so you can see where the name points. Those follow-up queries use the same resolver.

SPF and DMARC are not MX records. They live in TXT, including _dmarc for DMARC. The TXT lookup reads them.

Examples

  • Records with priority 10 and 20 are listed with 10 first.
  • A mail host with both IPv4 and IPv6 shows both addresses on its row.
  • A domain with no MX records gets the message "The domain has no MX records." Mail then falls back to the A record, which this page does not invent for you.

Limitations

  • The tool does not open port 25 or send a test message.
  • A mail host that itself is a CNAME is against the usual mail rules. If DNS still returns it, the row shows that name.
  • Null MX (a single dot, priority 0) means the domain does not accept mail. You will see that host as published.

Frequently asked questions

Which MX priority is used first?

The smaller number. Priority 1 is tried before priority 10. The word priority here is a preference value, not a rank label.

Why look up the mail host's addresses too?

MX stores a hostname. The A and AAAA queries show the addresses that hostname currently has, which is what a sending server connects to.

Where is the SPF record?

SPF is a TXT record that starts with v=spf1. Use the TXT lookup. It is not part of the MX set.

Often used together with the MX Lookup.

  • TXT Record Lookup

    TXT strings for a domain, with SPF and DMARC labeled, including the _dmarc name.

  • DNS Lookup

    One table of A, AAAA, MX, NS, TXT, SOA, and CAA records for a domain.