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Email deliverability

MX RecordMail Exchange record

Federico DonatoneBy · Updated October 15, 2026
Definition

An MX record (mail exchange record) is a DNS record that tells other mail servers where to deliver email for a domain. It points to one or more mail server host names, each with a priority number. Without a working MX record, a domain cannot receive email, and receivers may treat its outgoing mail as suspicious.

What is an MX record used for

DNS is the public address book of the internet. When someone emails anna@example.com, their mail server asks DNS for the MX records of example.com and gets back the names of the servers that accept mail for that domain. It then connects to one of them and hands over the message.

MX records only handle incoming mail. Outgoing mail is covered by SPF, DKIM and DMARC, which prove a message really comes from your domain. A healthy domain needs both sides working.

For outbound teams, MX records matter in two places. Your own sending domains need working MX records so replies and bounce notices reach a real inbox. Your prospect list needs them too: a contact at a domain with no MX record usually cannot receive email, so messages to that address come back as bounces.

How MX record priority works

Each MX record carries a priority number. Lower numbers are tried first. If two records share the same number, senders spread mail between them. Higher numbers act as backups when the first server does not answer.

MXexample.com10 mx1.example.comPriority 10 makes mx1.example.com the first server that senders try for mail addressed to example.com.
MXexample.com20 mx2.example.comPriority 20 makes mx2.example.com the backup, used only when mx1.example.com does not respond.

An MX record must point to a host name, never straight to an IP address, and that host name needs its own address record. On growthcab.com, the MX records point to Google Workspace (checked October 15, 2026). If you use Google Workspace or Microsoft 365, copy the exact values from the provider's admin setup page rather than from an old guide, since providers update them.

Common MX record mistakes

Many MX problems come from changes nobody finished. Look for these when mail goes missing:

  • Leftover records from a previous provider, which route some mail to a server nobody reads.
  • An MX record that points to an IP address or a CNAME alias instead of a host name.
  • Outreach domains with no MX record at all, so replies and bounce notices disappear.
  • A migration done without first lowering the record's cache time (TTL), so some senders keep using the old values for a while.
  • A typo in the host name, which breaks incoming mail without any visible error on your side.

How to check an MX record

  1. Run an MX lookup with a free DNS tool, or type nslookup -type=mx example.com in a terminal.
  2. Confirm every record points to your current mail provider, with no leftovers from an old one.
  3. Send a test email to an address on the domain and confirm it arrives.
  4. Check the sending domains you use for outreach the same way, so replies and bounce notices land somewhere a person reads.
From our workBefore a cold email campaign, remove every contact whose domain has no MX record. Those emails will almost certainly bounce, and each bounce counts against your sending domain.

Our free cold email domain checker tests MX alongside SPF, DKIM and DMARC, and the lead list QA skill on our free tools page flags domains with no mail server. For sending setups that keep failing, see our email deliverability consultant service and the cold email deliverability checklist.

MX Record FAQ

Do I need an MX record to send email?
Strictly speaking, MX records control incoming mail, so sending can work without one. In practice, a sending domain without MX records cannot receive replies or bounce notices, and receiving servers may trust it less. Every domain you send from should have working MX records.
What happens if a domain has no MX record?
Some senders fall back to the domain's address record, but most domains without an MX record simply do not receive email, and messages to them bounce. That is why lead list checks remove contacts at domains with no mail server before a campaign starts.
Can a domain have more than one MX record?
Yes. Many setups publish several MX records for redundancy, each with its own priority number. Senders try the lowest number first and move to the next one only if that server does not answer.

Related terms

SPF RecordAn SPF record (Sender Policy Framework) is a TXT record in a domain's DNS that lists the mail servers allowed to send email for that domain. Receiving servers check it to spot forged senders. A missing or broken SPF record makes your email more likely to be rejected or filtered to spam. DKIMDKIM (DomainKeys Identified Mail) is an email authentication method that adds a digital signature to every outgoing message. The receiving server uses a public key published in the sender's DNS to check that signature. A valid signature proves the email came from that domain and was not altered on the way. DMARCDMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS record that tells receiving mail servers what to do with email that uses your domain but fails authentication: deliver it, send it to spam or block it. It builds on SPF and DKIM and sends you reports on who is sending email as your domain. Email DeliverabilityEmail deliverability is the share of your sent emails that reach the recipient's inbox instead of bouncing or landing in spam. It depends on four things: authenticated sending domains, a verified contact list, a steady daily volume per mailbox, and messages relevant enough that recipients do not report them as spam.

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