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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallTo check which mail servers DNS publishes for a domain, run dig example.com MX in a terminal, replacing example.com with the domain you want to inspect. On Windows, use nslookup, then enter set q=mx and the domain name. The result shows the mail exchanger hostnames and their preference values; it is a point-in-time DNS answer, not proof that mail delivery works.
Check MX records with dig
On macOS, Linux, or another system with dig installed, query the domain’s MX records explicitly:
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dig example.com MXTo print only the answer records, use:
dig example.com mx +shortReplace example.com with the domain, such as yourdomain.com. Cloudflare recommends the short form when troubleshooting email: compare the returned mail-server hostnames with the values in your DNS provider’s records page and the email provider’s setup instructions. See Cloudflare’s email troubleshooting guide.
Check MX records on Windows
Microsoft documents nslookup as a DNS diagnostic utility for supported Windows versions, including Windows 10 and 11. Open Command Prompt and query MX records at the interactive prompt:
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- Enter
nslookupand press Enter. - Enter
set q=mxand press Enter. - Enter the domain name, such as
example.com, and press Enter.
The response includes a preference value and a mail exchanger hostname. Microsoft provides this procedure in its SMTP-domain nslookup example; the nslookup command reference describes the utility and supported Windows versions.
Read the MX lookup result
An MX record gives a preference number and the hostname of a mail exchanger. For example, in 10 mail.example.com, 10 is the preference and mail.example.com is the exchanger hostname.
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- Lower preference numbers are preferred. A record with preference 10 is preferred over one with preference 20, according to the DNS and SMTP standards. See RFC 1034.
- Equal numbers do not identify a single primary server. When multiple exchangers have the same preference, SMTP permits the sending system to choose between them; RFC 5321 describes randomized choice when there is no clear reason to favor one. See RFC 5321.
- The target is a hostname, not an IP address. That hostname needs to resolve to one or more A or AAAA address records. RFC 5321 says an MX target that resolves through a CNAME is outside the standard’s requirements, so MX records should point to hostnames with address records rather than CNAME aliases.
What it means when a lookup returns no MX records
An empty MX answer is not automatically proof that a domain cannot receive email. Under SMTP’s implicit-MX rule, when a domain has no MX records, senders may treat the domain itself as the mail exchanger, provided it has usable address records. This differs from an explicit null MX.
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A result of 0 . is a null MX: preference zero and a dot as the exchange value. It signals that the domain does not accept email. A domain publishing a null MX must not publish any other MX record, as specified by RFC 7505.
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Lookup errors are different from an empty answer
NXDOMAIN means the queried domain does not exist in DNS; it is not the same as a valid response with no MX records. A temporary lookup failure is also different: SMTP calls for temporary errors to be retried later. These distinctions are described in RFC 5321.
Use the result to troubleshoot email setup
- Run the lookup and note every preference number and exchanger hostname it returns.
- In your DNS provider’s records page, check that the configured MX values match the email provider’s exact setup instructions. Cloudflare recommends this comparison in its email troubleshooting documentation.
- If the live result differs from the provider’s required values, confirm the correct settings with that provider before editing DNS. Avoid replacing records based only on a guess about which hostname should appear.
- If records look correct but messages still fail, treat the lookup as one diagnostic check: it shows what a resolver sees, not whether mail routing, the mailbox, or the rest of the email configuration is working.
DNS answers can change and may differ temporarily between resolvers while records or caches update, so a lookup reflects what the queried resolver sees at that moment.
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Check MX records without a terminal
A browser-based DNS lookup can be useful if you cannot run dig or nslookup. Choose a lookup tool that lets you request the MX record type, enter the domain, and inspect the preference and exchanger fields. Do not assume a result from one resolver represents every resolver’s current view.
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