MX Record (Mail Exchange Record) (MX Record)

Security Glossary - DNS

Definition: An MX record specifies the mail server responsible for receiving email on behalf of a domain. Each MX record includes a priority value (lower numbers = higher priority) and a hostname. When someone sends email to user@yourdomain.com, their mail server looks up your MX records to find where to deliver the message.

Why MX Record Is Important

Without correct MX records, your domain cannot receive email. This affects everything from customer communications to password reset flows, support tickets, and business correspondence. Misconfigured MX records cause emails to bounce, which can also damage your domain's sender reputation.

MX records support redundancy through priority values. You can configure a primary mail server (priority 10) and backup servers (priority 20, 30) that accept mail when the primary is down. This prevents email loss during server maintenance or outages.

MX records also interact with email authentication. SPF records should include your MX servers as authorized senders. If your MX records point to a third-party email provider (like Google Workspace or Microsoft 365), your SPF, DKIM, and DMARC records must be configured to match. Inconsistencies between MX and authentication records can cause email delivery failures.

How to Verify

Use a DNS health checker to verify your MX records are correctly configured. The tool shows each MX record with its priority and target hostname. Verify the target hostnames resolve to actual mail servers and that the priority ordering is correct.

Configuration Reference

ParameterValue
Record TypeMX
Points toMail server hostname (not IP)
PriorityLower number = higher priority
Common setupTwo MX records for primary and backup
Cannot point toCNAME or IP address directly

See how your site handles MX Record

Check DNS Health

Common Questions About MX Record

What priority should my MX records have?
Lower numbers indicate higher priority. A typical setup uses 10 for the primary server and 20 or higher for backups. If you use a provider like Google Workspace, they specify the exact MX records and priorities to configure.
Can I have MX records without a mail server?
If your domain does not receive email, you can set a null MX record (priority 0, target '.') per RFC 7505. This tells sending servers that your domain does not accept email, preventing wasted delivery attempts. You should also set a DMARC policy to reject spoofed emails from your domain.
Disclaimer: DomainOptic provides automated informational scans only. Results do not constitute professional security advice, compliance certification, or a guarantee of security. Always verify findings independently.