Glossary
DNS RECORDS

MX Record

Mail Exchange record — a DNS record that specifies the mail servers responsible for receiving email for a domain, with priority values to control which server is tried first.

An MX record (Mail Exchange) tells sending mail servers where to deliver email for a domain. When someone sends email to user@example.com, their mail server looks up example.com’s MX records to find the destination.

Format

example.com.  3600  IN  MX  1   aspmx.l.google.com.
example.com.  3600  IN  MX  5   alt1.aspmx.l.google.com.
example.com.  3600  IN  MX  10  alt3.aspmx.l.google.com.

Lower priority number = higher preference. If the priority-1 server is unreachable, the sender tries priority-5, then priority-10.

Rules

  • MX records must point to a hostname (A/AAAA record), not an IP address
  • MX cannot be a CNAME — RFC 5321 requires direct hostname resolution
  • A domain with no MX record causes email to fall back to the domain’s A record IP (rarely intentional)

Common Providers

ProviderMX Record
Google Workspaceaspmx.l.google.com
Microsoft 365yourdomain.mail.protection.outlook.com
Zoho Mailmx.zoho.com
Self-hostedYour mail server hostname

Parked domains with no email should have no MX records — this signals to senders that the domain doesn’t accept email, preventing backscatter spam.

Browse every major DNS record type, check the TXT record glossary entry, or read what an SPF record is — SPF is a TXT that governs which MXes may send.

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