MX lookup: find a domain's mail servers
Enter a domain below and this free tool looks up its mail exchanger (MX) records and their priorities, then makes a second round of A/AAAA lookups for up to 5 of the listed mail hosts, so you can see at a glance whether a host that is correctly listed can actually receive mail, not just whether it appears in the record.
Keep this result
Copy a link to this check so you can share it or run it again later. Want a heads-up if something changes? That's early access, not a live feature yet — tell us and we'll set it up by hand.
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 — see what MX record priority actually does for ties, missing records and other edge cases. Once mail is routed to the right host, check that it is also authenticated correctly — see SPF, DKIM and DMARC explained. For a full walkthrough of this result’s priority column and host-resolution check together, see how to read an MX lookup result.
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/.
Reference: MX record.
Frequently asked questions
What does MX priority mean?
Lower numbers are tried first: RFC 1035 defines the MX preference field as a plain ranking where "lower values are preferred" (RFC 1035 §3.3.9), so a domain can list several MX hosts as fallbacks, most-preferred to least.
A domain has no MX record — can it still receive mail?
Sometimes, but it's not guaranteed: some mail software falls back to treating the domain's own A/AAAA record as an implicit mail host, a convention from the original SMTP specs (RFC 5321), but not every sending server honors that fallback. A domain that actually sends or receives mail should publish MX records explicitly rather than rely on it.
What happens if two MX records share the same priority?
Two (or more) MX records sharing one preference value are treated as a single equally-ranked group: per RFC 1035's MX preference field (§3.3.9), sending servers may try either host, in either order, as a simple form of load balancing — neither is preferred over the other.
Does a resolving MX host mean mail will actually be delivered?
No — this confirms the host has an A/AAAA record, not that it accepts mail on port 25, has a working mail server, or isn't rejecting messages. That needs a live SMTP test, which this tool does not perform.