MX Record Lookup

Inspect the authoritative mail route, verify that preferred exchangers have DNS addresses, and identify configuration problems without pretending to send email.

Authoritative MX evidence
Null and implicit MX handling
Preferred-target A and AAAA checks
DNSSEC and delegation context

Domain or email address

URLs, trailing dots, email addresses and internationalized names are normalized. IP addresses are not valid mail domains.

Expected MX routes (optional)

One target per line. Include priorities for an exact route comparison, or enter hostnames only.

Advanced DNS options

Discovery resolver

Used to discover delegation and DNSSEC evidence. MX answers are then requested directly from authoritative servers.

Run protocol checks
Also compare plain UDP, EDNS with the DNSSEC OK flag, and TCP against authoritative endpoints. This can take longer.

Waiting

MX result

Published routes —

First preference —

Address evidence —

Authority —

Mail delivery order

Senders try the lowest preference number first. Equal values form a peer pool; a larger number is a fallback, not a faster route.

MX routes and target address evidence
Role	Preference	Mail exchanger	DNS address	MX TTL	Validation

Findings and next actions

Each warning states what was observed, why it matters, and what to check next.

Mail-exchanger address evidence

Preferred or suspicious targets are independently checked. Remaining rows may use additional-section address hints, which are useful but not independent proof.

A and AAAA evidence for MX targets
Target	Check level	IPv4	IPv6	Alias path	Result

Authoritative nameserver evidence

Every returned authoritative endpoint is shown separately so split answers, timeouts and stale servers are not hidden by a single consensus row.

Direct authoritative MX observations
Nameserver	Endpoint	Status	Answer	TTL	DNS time

DNS diagnostics

Delegation and DNSSEC problems can prevent otherwise correct MX records from being usable.

Delegation and zone evidence

DNSSEC validation

UDP, EDNS and TCP checks

DNS protocol evidence from authoritative servers
Nameserver	Endpoint	UDP	EDNS + DO	TCP

Raw diagnostic evidence

How to read this MX result

PreferenceLower numbers are attempted first. Several records with the same number are peers, not backups to one another.
Null MXA single “0 .” record deliberately says the domain accepts no email. It is healthy when intentional and published alone.
Implicit MXIf no MX exists but the domain has an address, SMTP may try that domain directly at preference 0. Explicit MX is clearer operationally.
Addressable targetAn MX target must resolve directly to at least one A or AAAA address. This does not prove that SMTP is listening or accepts recipients.
Authoritative agreementEvery delegated nameserver should return the same RCODE and MX RRset. A split can route senders differently.
TTLThe MX TTL is how long resolvers may cache this route set. It is not a guaranteed propagation countdown.

Standards referenced by the diagnostics include RFC 1035, RFC 2181 §10.3, RFC 5321 §5.1 and RFC 7505. No SMTP connection, mailbox verification, reputation or blacklist test is performed.