An MX (Mail Exchange) record tells the world which servers accept email for a domain. When someone writes to you@example.com, the sender mail server looks up the MX records of example.com to find where to deliver the message.
An MX lookup shows those records, their priority and the IP addresses of each mail server. Use it after changing email provider, or to find out why messages are not arriving.
The main parts of a result.
| Part | Meaning |
|---|---|
| Priority | Lower numbers are tried first. A server with priority 10 is used before one with priority 20. |
| Same priority | Servers with the same priority share the load between them. |
| Backup servers | Servers with a higher number are used when the main servers cannot be reached. |
| Mail server name | The host name of the server. It must have an A or AAAA record and should not be an alias (CNAME). |
| Null MX | A single record with priority 0 and the name "." says that the domain does not accept email. |
Problems that often stop email from arriving.
Quick answers about MX Lookup.
It sets the order in which servers are tried. The server with the lowest number is tried first.
To provide a backup or to share the load. Many email providers also ask you to publish several records.
Some senders try the address record (A or AAAA) of the domain as a fallback, but this is unreliable. Publish MX records instead.
Resolvers keep the old answer until its TTL runs out. Wait for the old TTL to pass, then search again.
No. It only shows where email is delivered. To check which servers may send email for the domain, use SPF Check.