MX Lookup

Read a domain’s mail routing

Enter the domain after the @ sign, not a full email address. An MX record names a mail exchange and its preference number. The tool sorts MX answers by numeric preference so lower values appear first.

Two targets with the same preference are peers. Their order in a resolver response does not establish a unique primary server. This tool does not connect to port 25, test a mailbox, or deliver a message.

example.com.  3600  IN  MX  10 mail.example.com.

DOCUMENTATION EXAMPLE — not a live DNS response

What Null MX means

An MX record with preference 0 and target a single dot explicitly says the domain does not accept email. This is a Null MX declaration, not a mail server called dot. No address lookup is attempted for that target.

No MX record is different from Null MX: SMTP standards may use address records as an implicit fallback in some circumstances. An absent MX alone is not a universal delivery-failure diagnosis.

Supplemental addresses and limitations

A and AAAA lookups can show addresses attached to returned exchange names. These are DNS observations only. They do not check whether a mail server is reachable, whether its TLS configuration is correct, or whether it accepts the intended recipient.

Address enrichment is limited to eight distinct targets to keep a browser operation bounded. Any failed supplemental query is displayed separately rather than hiding successful MX records.

When email still does not arrive

Check SPF and DMARC configuration next, but remember that published policies are not a delivery guarantee. Sender reputation, authentication alignment, filtering, mailbox rules and remote SMTP behavior are outside an MX lookup.

Compare results from the same resolver and type before diagnosing a discrepancy. Allow for the recorded TTL rather than assuming a fixed 24- or 48-hour propagation period.