MX lookup: find a domain's mail servers
See the mail exchanger (MX) records for a domain, their priorities, and whether the hosts they point to resolve, with a second round of A/AAAA lookups for up to 5 mail hosts so you can spot a listed host that cannot actually receive mail.
How it works and limits
This tool queries the same DNS-over-HTTPS proxy as the general DNS lookup tool, filtered to the MX type, then makes a second round of A and AAAA lookups for each mail host so you can see at a glance whether they actually resolve — a host with no A/AAAA record cannot receive mail even if it is correctly listed.
Reading the result
Each MX record has a priority number and a hostname. Sending servers try the lowest-priority (most preferred) host first and fall back to higher numbers if it is unreachable. Several MX records with the same priority are tried in any order, as a load-balancing group.
Limits
- This checks whether the mail hosts resolve in DNS, not whether they actually accept mail on port 25 — that needs a live SMTP connection, which this tool does not make.
- Up to 5 mail hosts are resolved per lookup to keep the result fast.
- No query is logged; see /legal/privacy/.
Frequently asked questions
What does MX priority mean?
Lower numbers are tried first; a domain can list several MX hosts as fallbacks.
A domain has no MX record — can it still receive mail?
Some mail software falls back to the A/AAAA record, but this is unreliable; a domain that sends or receives mail should publish MX records explicitly.