What an MX record is
An MX (mail exchanger) record names a server that accepts email for the domain. When someone sends mail to [email protected], their mail server looks up the MX records of example.com and delivers to one of them.
example.com. 3600 IN MX 10 mail1.example.com.
example.com. 3600 IN MX 20 mail2.example.com.The number is the priority. The lowest number is tried first. Here mail2 is only used when mail1 does not answer. Records with the same number share the load.
How to read the result
Each row shows the priority and then the server name. Check three things:
- The servers belong to the mail provider you actually use.
- No old provider is left in the list. Mail sent to a closed account there is lost or bounced.
- Each server name has its own A or AAAA record. An MX must point to a name, never to an IP address, and not to a CNAME.
Common MX mistakes
- No MX record. Senders fall back to the domain's A record, which is usually a web server that does not accept mail.
- A typo in the server name. Mail queues at the sender for days, then bounces.
- Both old and new providers listed. Some mail arrives at each. Remove the old records once the move is done.
- A domain that sends no mail and has no record saying so. A "null MX" (
0 .) tells senders at once that the domain accepts no mail.