Domain Health · MX
MX record checker
Lists the mail servers for a domain in priority order, checks each one resolves, and points out setups that make mail bounce.
How MX records work
MX (mail exchanger) records tell other servers where to deliver email for your domain. Each has a priority number; lower numbers are tried first, and servers with equal numbers share the load.
10 mx1.example-mail.com
20 mx2.example-mail.com
Problems that cause bounces
No MX records
Senders then try the domain's A record, which usually points to a web server that doesn't accept mail. If you receive email at the domain, add the MX records your provider gives you. If you never do, publish a "null MX" (priority 0, host .) so senders fail immediately instead of retrying for days.
An MX pointing at an IP address
MX values must be hostnames. Create an A record such as mail.yourdomain.com for the IP, then point the MX at that name.
A hostname that doesn't resolve
Usually a typo, or a leftover record from a provider you've left. Fix or remove it; a dead high-priority server delays every message.
An MX pointing at a CNAME
The DNS standards say MX targets must not be aliases. Many senders cope, some don't. Point the MX at the final hostname instead.
Changing email providers
When you move providers, replace all old MX records at once with the new ones. Mixing old and new servers splits incoming mail between two mailboxes. Lowering the records' TTL a day before the switch makes the change take effect faster.