MX records are DNS records that tell other mail systems where to deliver email for a domain. MX stands for Mail Exchanger.
If you are searching for , , or , the practical answer is simple: MX records control inbound mail routing for a domain.
Quick answer
MX records define:
- which mail servers receive mail for a domain
- the priority order for those servers
- how other systems should route inbound messages
If MX records are missing or wrong, the domain may stop receiving mail correctly.
What an MX record actually does
When someone sends mail to , the sending system needs to know which server should receive mail for .
It checks DNS for MX records and uses them to determine:
- destination mail servers
- failover order
- whether the domain is configured for mail at all
This is why MX records are foundational to inbox delivery even before SPF, DKIM, and DMARC are involved.
Example MX records
An MX configuration often looks like this:
That means:
is the preferred destinationis the backup or lower-priority option
Lower numbers indicate higher priority.
How to read an MX lookup result
When you query a domain, the useful output is usually:
- the hostnames listed as mail destinations
- the priority number for each hostname
- whether those hostnames resolve correctly
That matters because a syntactically valid MX record can still point to the wrong provider or a broken host.
How MX priority works
Priority values help sending servers choose where to deliver mail first.
| Priority value | What it means |
|---|---|
| Lower number | Higher preference |
| Higher number | Lower preference |
| Equal values | Load-sharing or implementation-dependent behavior |
Priority is not the same thing as sender trust. It is purely about inbound routing order.
MX records vs SPF, DKIM, and DMARC
These records solve different problems.
| Record type | Purpose |
|---|---|
| MX | Inbound mail routing |
| SPF | Authorized outbound senders |
| DKIM | Signed outbound message integrity |
| DMARC | Alignment and receiver policy |
Teams often confuse MX with SPF because both live in DNS. MX is about where mail goes. SPF is about who is allowed to send.
How to check MX records
Use this sequence:
- query DNS for the domain's MX records
- confirm there is at least one valid mail destination
- confirm priorities make sense
- verify target hosts resolve properly
- confirm the mail system behind those hosts is the intended provider
MX checks are especially useful during:
- provider migrations
- new domain setup
- inbound routing failures
- email verification workflows
MX record migration checklist
If a domain is moving between mail providers:
- document the current MX targets
- lower DNS TTL if appropriate
- publish the new provider targets
- verify all MX hosts resolve correctly
- confirm mail reaches the new system
- check related SPF, DKIM, and DMARC posture after the change
MX changes often look small in DNS but have immediate production consequences.
Common MX record problems
No MX records published
If no MX records exist, many systems treat the domain as not configured for mail.
Wrong provider targets
The domain points to an old provider or incomplete migration target.
Priority order does not reflect intent
Backup systems are accidentally preferred over primary systems.
Target hostname does not resolve correctly
The MX record points to a hostname with broader DNS problems.
MX records and verification workflows
MX checks are part of many verification processes because they help answer whether a domain can receive mail at all.
Useful related pages:
MX troubleshooting table
| Symptom | Likely cause | First check |
|---|---|---|
| Domain not receiving mail | Missing or wrong MX records | Query current MX entries |
| Mail routing to wrong system | Stale provider targets | Compare MX with actual provider |
| Intermittent inbound failures | Priority or target-host issue | Check all MX destinations |
| Verification tools mark domain risky | Weak or missing mail routing | Confirm MX exists and resolves |
Use MailSlurp for MX-dependent checks
MailSlurp is useful when MX health affects signup, verification, or inbound workflow reliability. Teams often pair DNS lookup with Check Email Verification to confirm that domains can actually receive mail before release or migration work. Create a free account at app.mailslurp.com if you want those checks connected to broader email testing.
FAQ
What are MX records in simple terms?
They are DNS records that tell mail systems where to deliver email for a domain.
What does MX priority mean?
Lower numbers are preferred first.
Can a domain send mail without MX records?
Sometimes outbound mail can still leave a system, but inbound delivery depends on correct routing and receiving configuration.
Are MX records the same as SPF?
No. MX is inbound routing. SPF is outbound sender authorization.
Final take
MX records are one of the basic controls behind inbound email. If a domain is not receiving mail correctly, MX should be one of the first places you check.