MX Lookup

Query Mail Exchange (MX) DNS records for any domain — see mail servers and their priority

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Frequently Asked Questions

An MX (Mail Exchange) record is a DNS record that specifies which mail servers are responsible for receiving email for a domain. When someone sends an email to user@example.com, the sending mail server performs an MX lookup for example.com to find out where to deliver the message.

Priority (also called preference) is a number that determines which mail server should be tried first. A lower number means higher priority. For example, a server with priority 10 is tried before one with priority 20. If the primary server is unreachable, email is retried on the next-priority server. This provides redundancy.

If a domain has no MX records, it cannot receive email. This is common for domains used only for websites, API services, or subdomains. Some domains fall back to their A record for mail delivery (implicit MX), but this is not reliable or recommended. You should always set explicit MX records if you need to receive email.

The MX hostname usually reveals the provider: google.com in the hostname means Google Workspace (Gmail), outlook.com or protection.outlook.com means Microsoft 365 / Exchange Online, mimecast.com means Mimecast, pphosted.com means Proofpoint. Self-hosted mail servers often use the domain itself as the MX record.

About MX Lookup

What This Tool Does

This tool performs a real-time DNS MX record query for any domain and returns all mail exchange records sorted by priority. It also resolves each mail server's hostname to its IP address for quick verification.

Common Use Cases
  • Verify email is configured for a domain
  • Identify which email provider is used
  • Troubleshoot email delivery issues
  • Check MX record propagation after DNS changes
  • Security research and phishing detection