MX lookup
MX records tell the internet which servers accept email for a domain. Enter a domain to list its mail servers in priority order, with TTLs, and compare Cloudflare's and Google's answers to catch a change that hasn't finished propagating.
- Free, no subscription
- No account
- Part of the DNS Lookup
What it checks
- Every MX record with its priority and target host.
- TTLs, so you can estimate how long old answers stay cached.
- Differences between Cloudflare and Google answers after a change.
- Domains with no MX record, or a null MX that refuses email.
How MX priority works
Each MX record has a priority number; lower numbers are tried first. Two records with the same number share the load, and higher numbers act as backups. Hosted email services usually publish one or more records with their own host names, for example Microsoft 365 uses a host ending in mail.protection.outlook.com and Google Workspace uses smtp.google.com or aspmx.l.google.com.
Common MX problems
After an email migration, old MX records left in place can send some mail to the previous provider. MX records must point to a host name, never directly to an IP address, and the host shouldn't be a CNAME. A domain with no MX record may still receive mail at its A record, which is rarely intended; a domain that should never receive mail can publish a null MX instead.
Frequently asked questions
What does MX priority mean?
Lower numbers are preferred. Senders try the lowest-priority server first and fall back to higher numbers if it's unavailable.
How long do MX changes take to apply?
Up to the TTL of the old record, often between minutes and a day. The TTL column shows it.
What is a null MX?
A single MX record pointing to "." with priority 0. It declares that the domain accepts no email.
How do I check the rest of my email setup?
Use the Email Security Checker for SPF, DKIM, DMARC and provider detection in one check.
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