A missing usable MX record means other mail systems cannot discover where to deliver messages for the domain. Senders then see bounces such as “No MX record found” or “Domain not found”, and sign-up forms that validate addresses may reject the domain. The fix is usually one record at the right DNS provider, but the error can also come from a typo, the wrong host or a null MX. Work through the steps below.
Confirm the error
Run MX Lookup for the domain. If it returns no MX answer, also check the exact spelling of the domain and whether the error refers to a subdomain such as mail.example.com, which needs its own MX record if it should receive mail.
From a terminal, dig +short MX example.com shows the same public answer. An empty result means no MX record is published at that name.
dig +short MX example.com
# healthy answer, for example:
10 mx.freedomainmail.com.Confirm where DNS is authoritative
Check the domain nameservers, then edit records at that provider rather than whichever registrar account is easiest to find. If the NS records point to Cloudflare, records added at the registrar have no effect.
Run MX Lookup and compare its public answer with the target supplied by the mailbox provider.
Publish and verify safely
Add the complete MX target and its priority. Use @ (or leave the host blank) for the root domain. Remove old MX records only as part of a planned migration.
Wait for the prior TTL, check again, then send a message from an external account.
Type Name / Host Value Priority
MX @ mx.freedomainmail.com 10Rules an MX record must follow
The value must be a hostname, not an IP address. If your server only has an IP, create an A record such as mail.example.com and point the MX at that name. The MX target should not be a CNAME either; point it at a name that has its own A or AAAA record.
Lower priority numbers are preferred. When several records exist, senders try the lowest first; see MX priority explained.
MX @ 10 203.0.113.25 ✗ IP address
MX @ 10 mail.example.com ✓ with:
A mail 203.0.113.25Null MX and the A-record fallback
If the domain has no MX record at all, RFC 5321 lets senders fall back to the domain's A or AAAA record. Do not rely on that: many systems treat the domain as unable to receive mail, and the web server usually does not accept mail.
A record of 0 . is a null MX (RFC 7505). It deliberately says the domain accepts no mail, so senders fail immediately. Remove it if the domain should now receive mail. To set up receiving end to end, follow the setup guide or the DNS Checker.
Common mistakes to avoid
- Adding the MX record at the registrar while another provider's nameservers are active.
- Entering an IP address as the MX value.
- Typing the full domain into a host field that appends it, creating example.com.example.com.
- Leaving a null MX (0 .) in place after deciding to receive mail.
- Testing before the previous negative-cache TTL has expired.
Frequently asked questions
Can an A record replace MX?
Mail delivery may historically fall back to an address record, but a deliberate MX record is the reliable configuration.
What does MX priority mean?
Lower numbers are preferred. Follow the provider's complete priority set.
Why do I still see “No MX record” after adding it?
Resolvers cache negative answers too, for the time set in the zone's SOA record. Wait, then check again from outside your network.
Does a subdomain need its own MX?
Yes, if it should receive mail. MX records do not inherit from the parent domain.
Can I point MX at a CNAME?
No. The MX target should be a hostname with its own A or AAAA record.