What Are MX Records?

MX (Mail Exchanger) records tell the internet which mail servers handle email for your domain. Each MX record has a priority value, where lower numbers mean higher priority.

Example

example.com.  300  IN  MX  10  mail.example.com.
example.com.  300  IN  MX  20  backup.example.com.

If the primary server (priority 10) is down, email routes to the backup server (priority 20).

Common MX Configurations

Google Workspace — aspmx.l.google.com (priority 1)
Microsoft 365 — *.mail.protection.outlook.com
Zoho Mail — mx.zoho.com (priority 10)
ProtonMail — mail.protonmail.ch (priority 10)

No MX Records?

If no MX records exist, email servers will fall back to the domain's A record. This is not recommended for production email.

What an MX lookup shows

An MX (Mail Exchanger) record tells the rest of the internet which servers accept email for your domain. This tool asks Google Public DNS for the MX records of any domain and lists each mail server with its priority and TTL.

How to read the results

Priority is the number before the hostname. Lower numbers are tried first, so 5 mx1.example.com is preferred over 10 mx2.example.com. Equal priorities share the load.
An MX value must be a hostname, never a bare IP address, and it should not point to a CNAME.
A single record that reads 0 . is a "null MX": the domain deliberately accepts no email.
No result at all means the domain publishes no MX, so mail to it may fail or fall back to the domain's A record.

Common problems it helps you spot

Old host left behind. After moving to Google Workspace or Microsoft 365, leftover MX records from the previous provider send some mail to the wrong place. Remove them.
Two providers at the same priority. Mail is split between them at random.
A change that has not spread yet. Resolvers cache the old answer until the TTL expires. Compare several resolvers with the DNS propagation checker.

Next, confirm sending is trusted too: check the domain's SPF, DKIM and DMARC records. Our guide to checking MX records walks through a full email migration.

MX Lookup