What Is an MX Record?

What Is an MX Record?

An MX (Mail Exchange) record is a DNS record that specifies mail servers responsible for receiving email for a domain. MX records enable email routing by telling sending mail servers which mail servers to deliver emails to for a specific domain.

MX records include: mail server hostname (e.g., mail.example.com), priority value (lower numbers = higher priority), and preference order (multiple MX records for redundancy). MX records are essential for email delivery - without MX records, emails cannot be delivered to a domain.

Check MX records using our MX lookup tool to verify email delivery configuration. Learn more about DNS and DNS lookup.

MX Record Purpose

Email Routing

MX records specify which mail servers should receive emails for a domain, enabling email routing and delivery.

Mail Server Identification

MX records identify mail servers by hostname, allowing sending mail servers to find and connect to receiving mail servers.

Email Delivery

Without MX records, emails cannot be delivered to a domain. MX records are essential for email delivery functionality.

Redundancy

Multiple MX records with different priorities provide redundancy, ensuring email delivery even if primary mail servers are unavailable.

Load Balancing

Multiple MX records with the same priority enable load balancing, distributing email delivery across multiple mail servers.

MX Record Format

Record Format

MX records follow this format: priority mail-server-hostname

Example MX Record

10 mail.example.com - Priority 10, mail server mail.example.com

Priority Values

Priority values range from 0 to 65535. Lower numbers indicate higher priority (preferred mail servers).

Mail Server Hostname

Mail server hostname must resolve to an A or AAAA record (IP address), not a CNAME record.

Multiple MX Records

Domains can have multiple MX records with different priorities for redundancy and load balancing.

MX Record Priority

Priority System

MX records use priority values to determine delivery order. Lower priority numbers indicate higher priority (preferred mail servers).

Priority Examples

• 10 mail1.example.com - Primary mail server (priority 10)
• 20 mail2.example.com - Secondary mail server (priority 20)
• 30 mail3.example.com - Tertiary mail server (priority 30)

Delivery Order

Sending mail servers attempt delivery to mail servers in priority order (lowest priority number first).

Failover

If primary mail server (lower priority) is unavailable, sending servers attempt delivery to secondary mail servers (higher priority numbers).

Same Priority

Multiple MX records with the same priority enable load balancing, with sending servers choosing randomly or round-robin.

Checking MX Records

1. MX Lookup Tools

Use our MX lookup tool to query MX records and retrieve mail server information for domains.

2. Command Line Tools

Use command-line tools (dig, nslookup) to query MX records: dig MX example.com

3. Domain Health Check

Use our domain health check to verify DNS configuration including MX records.

4. Verification

Verify MX records are published correctly, mail server hostnames resolve to IP addresses, and priorities are configured appropriately.

5. Email Delivery Testing

Test email delivery to verify MX records are working correctly and emails are being delivered to the correct mail servers.