MX Record Checker
Look up your domain’s mail servers, review MX priorities and identify DNS configuration issues.
Enter your receiving mail domain. We check public MX, A and AAAA records without connecting to mail servers.
No registration required. Checks run on our server using Google Public DNS. Our DNS cache lasts up to five minutes; upstream DNS caches can delay changes further. No email test allowance is used.
How to use MX Record Checker
- Find the domain after
@in the receiving email address, or check which domain you configured in your mailbox provider’s administration panel. - Enter the domain only. For
person@example.com, enterexample.com, without the mailbox name, a URL or a mail server hostname supplied by the provider. - Select Check MX. The domain is required and there are no optional fields. The lookup inspects public DNS without opening an SMTP connection.
- Compare the listed servers and priorities with your provider’s setup instructions. If no MX exists, read the fallback finding; if Null MX appears, confirm whether receiving mail is intentionally disabled.
What this tool checks
The checker queries Google Public DNS from our server and displays MX records in ascending priority order, with each record’s reported TTL (time to live) in seconds.
- Domain existence, MX priority and target syntax, and whether the response contains usable mail server hostnames.
- A and AAAA address records for each inspected target, representing IPv4 and IPv6 respectively. A target needs at least one address family, not both.
- CNAME aliases returned for MX targets, which should instead point directly to hostnames with address records.
- Valid Null MX (
0 .), conflicting Null MX settings, or A/AAAA fallback at the input domain when no MX record is published.
Target inspection is bounded: at most 31 distinct non-null targets are inspected, and overall DNS limits can stop it sooner. Unchecked or incomplete targets are marked Unknown. The tool does not test port 25, server uptime, mailbox existence, authentication, TLS or actual delivery.
Understanding your results
Lower priorities are preferred. Review your receiving servers here, then compare their hostnames with your MTA-STS policy. DNS configuration alone does not prove delivery.
| Finding | Meaning & likely cause | Next action |
|---|---|---|
| Pass: MX / address records | Usable MX hostnames were found, or a target has A and/or AAAA records. | Confirm they are the hosts your provider expects; DNS resolution alone does not prove they accept mail. |
| Fail: domain existence | DNS returned NXDOMAIN for the requested domain. It may be misspelled or incorrectly delegated. | Check the spelling, registration and authoritative DNS delegation. |
| Info: no MX / implicit fallback | No explicit MX is published; the domain may have A/AAAA addresses that SMTP can try instead. | Publish explicit provider-supplied MX records if the domain should receive mail. |
| Warning: no fallback addresses | No MX or A/AAAA receiving destination was found. | Configure receiving DNS if mail is expected. A web-only domain may intentionally have no mail service. |
| Info: valid Null MX | The sole record is 0 ., explicitly declaring that this domain does not accept email. | Keep it if intentional. Replace it with real MX records when enabling inbound mail. |
| Fail: invalid Null MX / syntax / CNAME / no addresses | Records conflict, a target is malformed or an alias, or an inspected target has no A/AAAA records. | Correct the named MX record or its target’s address records using the mail provider’s instructions. |
| Unknown: DNS / target / fallback | A resolver error, incomplete address lookup or inspection limit prevents a conclusion. A table cell saying Unknown is not the same as None. | Retry or inspect the named target separately. Resolve persistent DNS errors before concluding the destination is absent. |
What is an MX record? Why does it matter?
An MX (Mail Exchange) record tells senders which hostname receives mail for a domain. It points to a mail server name, which in turn resolves to an IP address through A or AAAA records. That separates inbound mail routing from the domain’s website hosting.
How MX priority works
Lower numbers are preferred. Equal priorities and a single receiving server are both valid; they do not trigger a warning merely for that reason. Use this tool when moving mailbox providers or investigating routing errors. Once DNS looks right, check the MTA-STS policy for consistency with those receiving hostnames.
When moving receiving hosts, include their transport policy in the change plan. The MTA-STS and TLS-RPT setup guide explains how MX changes and policy coverage fit together.
Frequently asked questions
What if my domain has no MX records?
SMTP may use the domain’s A/AAAA addresses as an implicit fallback. Those addresses do not establish that an SMTP service is running. If no addresses exist either, this lookup has no receiving destination to report.
What is Null MX?
A single MX record with priority 0 and target “.” explicitly says the domain does not accept email and disables implicit fallback. It must not be combined with other MX records. This is useful for a domain that intentionally receives no mail.
Can an MX target be an IP address or CNAME?
Use the receiving server hostname supplied by your mail provider. An IP literal is not a valid MX target, and a CNAME alias is flagged as a configuration failure. The target should directly have A and/or AAAA records.
Why do I still see my old provider after changing MX?
Confirm that the change was made at the authoritative DNS host for the domain. TTL values in the results describe DNS caching in seconds. This service caches eligible answers for up to five minutes; upstream caches can retain previous records according to their expiry.
Does a passing result prove that a recipient mailbox exists?
No. The checker does not connect to a server or ask about any recipient. If a real delivery fails, inspect the sender’s bounce response and delivery log, then check the mailbox configuration with the receiving provider.