MX lookup
See which mail servers receive email for a domain, their addresses, and whether everything is set up to accept mail.
How the MX lookup works
We fetch your domain’s MX records, sort them by priority (lowest number first) and look up the IPv4 and IPv6 addresses of each mail server. For each address we check reverse DNS, the name an IP address points back to. We also recognise the provider behind the servers, such as Microsoft 365, Google Workspace, Zoho or a security gateway, which tells the other checks which settings to expect.
Common MX problems
- No MX records: other servers fall back to your website’s address, which usually can’t receive email. Add the MX records your email provider gives you.
- An MX record pointing at an IP address: not allowed. MX records must point at a host name.
- A host name that doesn’t resolve: often a typo or a server that was retired.
- Old records left behind after changing provider: some email still goes to the old system. Remove MX records for services you no longer use.
Domains that don’t use email
If a domain is only used for a website, publish a “null MX” record (priority 0, value .) together with v=spf1 -all and a DMARC policy of p=reject. That tells the world the domain never sends or receives email, so fraudsters can’t use it. Run the full email health check to see SPF, DKIM and DMARC alongside your mail servers.
What is an MX record?
It tells the world which servers accept email for your domain. Without one, other servers can’t deliver mail to you.
Why does Microsoft 365 show only one MX record?
That’s normal. A single Microsoft 365 or Google host name is backed by many servers behind the scenes, so one record is enough.
What is a “null MX”?
A record with priority 0 and the value “.”. It tells senders the domain never accepts email, which is right for domains used only for a website.
What is reverse DNS?
A lookup from an IP address back to a server name. Receiving servers use it as a basic trust signal for outgoing mail servers.