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MX record checker
Enter a domain. We list the mail servers that receive its mail, in priority order, and flag the setups where replies would bounce or fall over.
What an MX record is
An MX record says which servers accept mail for a domain. Senders look up the domain's MX records, then try the server with the lowest priority number first and fall back to the next. Unlike SPF, DKIM and DMARC, MX is not about proving who sent a message: it decides where replies arrive.
That matters for outbound. A domain you send cold email from needs a place for replies, bounce notices and unsubscribe requests to land, or they vanish.
| Part | What it means |
|---|---|
Priority (10, 20…) | Lower numbers are tried first. Equal numbers share the load. |
Host (smtp.google.com) | The name of the mail server. It must be a host name with its own address record. |
| One record vs several | Providers differ: some give one record, others a primary and backups. Copy what yours documents. |
Null MX (0 .) | A deliberate "this domain accepts no mail". Right for a domain that never receives; wrong on one that should get replies. |
Common errors and how to fix them
- No MX records
Replies to mail from this domain have nowhere to go, and a sender that finds no MX may fall back to the domain's web server address, which is not a mailbox. Bounces and unsubscribe replies are lost too.
Fix: Add your mailbox provider's MX records, or forward the domain's mail to a mailbox you read. - An IP address instead of a host
An MX record names a host. Putting an address in the host field does not work.
Fix: Create an A record for a host name, such asmail.yourdomain, and point the MX at it. - MX pointing at a CNAME
Some mail servers refuse to deliver when the MX host is an alias.
Fix: Point the MX at a host that has its own A or AAAA record. - Two providers' records mixed
After a migration, old records from the previous provider can sit beside the new ones, so some mail still goes to the old mailbox.
Fix: Delete the old provider's MX records once the new ones work. - Null MX on a domain that should get replies
The domain announces that it accepts no mail, so every reply bounces.
Fix: Replace the null record with your provider's MX records. - Wrong priority order
A backup server with a lower number than the main one receives mail first.
Fix: Give the main server the lowest number.
Examples
Illustrative records. Use the values your own provider documents.
One record, as Google Workspace documents it
yourcompany.com MX 1 smtp.google.comA primary and a backup
yourcompany.com MX 10 mail1.example.net
yourcompany.com MX 20 mail2.example.netA domain that accepts no mail (null MX)
yourcompany.com MX 0 .Questions
Does a sending-only domain need MX records?
If anyone can reply to it, yes: replies and bounces go to its MX. Teams often forward a secondary sending domain's mail to the main one, or give it a mailbox.
What does the priority number mean?
It is a rank, not a quantity: the lowest number is tried first. Servers with the same number are tried in any order.
Why does it name a provider?
We compare the MX hosts and the SPF record with the providers we have setup guides for, and link the guide when one matches.
MX looks right but mail still fails. What next?
MX only covers receiving. Check SPF, DKIM and DMARC for sending, and make sure the mailbox itself exists.
How long do changes take?
A record changes when its TTL expires at each resolver, so some senders see the new value before others. The TTL of the old record is the longest you will wait.
Outlevo checks this before every campaign
Outlevo warns when a sending domain has no place for replies.