MX Lookup

Check MX records for any domain online. Free MX record lookup to discover mail servers, view priorities, IP addresses, and verify email routing configuration.

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APIPOST /api/v1/email/mx
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Try also: SPF Checker
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Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is MX Lookup?

MX lookup retrieves the Mail Exchange records for any domain, revealing which servers are responsible for handling incoming email and in what order. The tool displays each mail server's hostname, priority value (lower numbers = higher priority), and resolved IP address. When a domain has multiple MX records, email is routed to the highest-priority server first, with lower-priority servers acting as fallbacks if the primary is unavailable.

This free MX record checker is essential for email administrators diagnosing delivery failures, system administrators verifying mail server configuration after migration, IT teams confirming that email services like Google Workspace, Microsoft 365, or Zoho Mail are correctly configured, and security researchers analyzing the email infrastructure of a domain. The tool queries authoritative DNS servers directly for accurate, real-time MX data rather than relying on cached results.

How to Use

  1. 1Enter the domain name to check its MX records (e.g., example.com)
  2. 2Click 'Run Check' to query authoritative DNS servers for Mail Exchange records
  3. 3Review the list of mail servers — each entry shows the hostname and priority value
  4. 4Check priority values: the server with the lowest number receives email first, others are fallbacks
  5. 5Verify that mail server hostnames resolve to valid IP addresses and are reachable
  6. 6Compare the results with your email provider's recommended MX configuration to ensure correctness

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

What are MX records and how do they work?
MX (Mail Exchange) records are DNS records that tell the internet which servers handle email for a domain. When someone sends an email to a domain, the sending mail server queries DNS for that domain's MX records to find where to deliver the message. Each MX record contains a mail server hostname and a priority number. The sending server tries the highest-priority server (lowest number) first. If that server is unavailable, it falls back to the next priority level. This system provides automatic failover for email delivery.
How do I find the mail server for a domain?
Enter the domain name in the MX Lookup tool and click Run Check. The tool will display all mail servers configured for that domain, their priority values, and resolved IP addresses. For example, Google Workspace domains typically show MX records pointing to servers like aspmx.l.google.com, while Microsoft 365 domains point to *.mail.protection.outlook.com. If no MX records exist, the domain cannot receive email through standard SMTP delivery.
Why is my email not being delivered to a domain?
Missing or misconfigured MX records are among the most common causes of email delivery failures. Use the MX Lookup tool to check: Are MX records present? If not, the domain can't receive email. Do the mail server hostnames resolve to valid IP addresses? Are the priority values correct? Is the mail server actually reachable on port 25 (SMTP)? Other common issues include SPF/DKIM/DMARC authentication failures, the sending server's IP being blacklisted, or the receiving server's mailbox being full or disabled.
What MX records should I use for Google Workspace?
Google Workspace requires five MX records with specific priorities: aspmx.l.google.com (priority 1), alt1.aspmx.l.google.com (priority 5), alt2.aspmx.l.google.com (priority 5), alt3.aspmx.l.google.com (priority 10), and alt4.aspmx.l.google.com (priority 10). After adding these records to your DNS, use this MX Lookup tool to verify they're configured correctly before completing your Google Workspace setup.
What does MX record priority mean?
The priority value (also called preference) determines the order in which mail servers are tried. Lower numbers mean higher priority. If your domain has MX records with priorities 10, 20, and 30, sending servers will always try the priority-10 server first. Only if that server is unavailable will they try priority 20, then 30. Servers with equal priority receive traffic in a round-robin fashion. This system ensures email delivery continues even if your primary mail server goes down.

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API Endpoint

POST /api/v1/email/mx
View Documentation