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About MX Lookup Online
This tool queries the MX (mail exchanger) records of any domain. The result shows the mail servers that accept email for that domain, along with their priority values (lower priority = higher preference).
MX lookups are essential for diagnosing email delivery problems: confirming the right mail servers are configured, verifying backup MX records exist, checking that a domain accepts mail at all (some don't), and tracing the chain when emails are bouncing.
Use it when setting up new email infrastructure, troubleshooting deliverability complaints, or investigating phishing emails that claim to come from a legitimate domain (compare the headers' Received-from server to the domain's actual MX).
How to use this tool
How to look up mail (MX) records
Enter the domain
Type the bare domain (e.g. example.com) into the Domain field — not the full email address. Up to 253 characters.
What MX records are
MX records tell the world which mail server accepts email for a domain, plus a priority value (lower = preferred). A domain without MX cannot receive mail at all.
Press Run
The server queries DNS for MX records and returns them sorted by priority. The lowest-priority host is tried first; subsequent hosts are fallbacks.
Use the result
Output is an mx array of { exchange, priority } pairs. Compare it to what your mail provider documented; mismatches mean your DNS is misconfigured.