MX record
An MX (mail exchanger) record says which servers receive email for a domain. When someone sends a message to you@example.com, their mail server looks up example.com's MX records and delivers to the server with the lowest priority number, trying the others if it can't get through.
| Record type | MX |
|---|---|
| Type number | 15 |
| Used for | |
| How common | Everyday |
| Defined in | RFC 1035, RFC 5321, RFC 7505 |
Format
<name> <ttl> IN MX <priority> <mail server>
| Field | What it means | Accepted values |
|---|---|---|
| Name | The domain that receives the email: @ for addresses like you@example.com. | A host name. |
| TTL | How long senders may cache the answer. | Seconds; 3600 is typical. |
| Priority | Order of preference. Lower numbers are tried first; equal numbers share the load. | 0 to 65535. Only the order between your records matters: 1 and 5 behave the same as 10 and 50. |
| Mail server | The host that accepts the mail. | A host name with its own A or AAAA record. Not an IP address, not a CNAME. . with priority 0 means the domain takes no email. |
Check an MX record
Type or paste a record in zone-file form (name, TTL, type, value) or just its value. Each part is explained as you type.
A valid MX record.
| Part | What it means |
|---|---|
| Name@ | @ means the domain itself (the root, or apex), such as example.com. |
| TTL3600 | Resolvers may keep this answer for 1 hour before asking again. Changes can take that long to reach everyone. |
| ClassIN | Internet. Every record you'll write uses IN. |
| TypeMX | Mail server for the domain. |
| Priority1 | Lower numbers are tried first. Servers with the same number share the load. 1 on its own means nothing; only the order between your MX records matters. |
| Mail serversmtp.google.com. | The host that receives this domain's email. It must have an A or AAAA record, and must not be a CNAME. |
Examples
Google Workspace
@ 3600 IN MX 1 smtp.google.com.
Google's current setup is a single MX. Older setups list five aspmx servers with priorities 1, 5, 5, 10, 10; both work.
Microsoft 365
@ 3600 IN MX 0 example-com.mail.protection.outlook.com.
The host name is your domain with dots replaced by hyphens; copy it from the Microsoft 365 admin centre.
Primary and backup
@ 3600 IN MX 10 mx1.example.net. @ 3600 IN MX 20 mx2.example.net.
Senders try mx1 first and fall back to mx2.
A domain that never receives email
@ 3600 IN MX 0 .
A null MX. Senders bounce mail straight away instead of retrying for days. Pair it with an SPF of v=spf1 -all and a DMARC p=reject.
How mail finds your server
The sending server asks DNS for the MX records of the part after the @. It sorts them by priority, looks up the A or AAAA record of the first host, and connects to it on port 25. If that fails, it tries the next. If a domain has no MX records at all, senders fall back to its A record, which is rarely what anyone wants.
MX records only control receiving. Which servers may send as your domain is set by SPF, DKIM and DMARC.
Changing email providers
- Lower the MX TTL to 300 a day before.
- Add the new provider's MX records and remove the old ones at the same time; mixing providers splits your mail.
- Update SPF to include the new provider and set up its DKIM key.
- Keep the old mailboxes open for a few days to catch mail from senders with cached records.
See it on a real domain
Or use the full MX lookup.
TTL
3600 is the usual choice. Lower it to 300 before switching providers. How TTL works
Common mistakes
- Pointing an MX at an IP address. It must be a host name.
- Pointing an MX at a name that is a CNAME. The standard forbids it and some senders refuse to deliver.
- Leaving the old provider's MX records next to the new ones, so some mail lands in the old mailbox.
- Adding MX records on a subdomain (mail.example.com) when you meant the domain itself (@).
- Treating priority as a percentage. It's an order: the lowest number gets all the mail while it's up.
At your DNS host
- Most dashboards have a separate Priority field; put only the host name in the value.
- Route 53 puts both in one value: 10 mail.example.com.
- Namecheap: under Advanced DNS, set Mail Settings to Custom MX to add your own.
- Cloudflare: MX records are never proxied, and the mail server's own A record must be DNS only (grey cloud).
Questions
What does MX stand for?
Mail exchanger: the server that exchanges (accepts) mail for the domain.
Do lower or higher MX priorities win?
Lower. A priority 1 server is tried before a priority 10 server. Servers with the same number share the mail.
Can I have email without an MX record?
Senders fall back to the domain's A record, but almost no web server accepts mail, so in practice no. Every domain that receives email needs MX records.
Does the MX record affect sending email?
No. MX only controls where mail to your domain is delivered. Sending is covered by SPF, DKIM and DMARC.
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