MX Lookup Tool
Check mail exchange records for any domain
Only public email providers are listed; no private domains are displayed to protect user privacy.
This page provides original, human-reviewed information about MX record lookups, covering priority-based routing, fallback mail servers, and the relationship between MX targets and A/AAAA records.
MX (Mail Exchange) records are DNS records that specify the mail servers responsible for accepting email messages on behalf of a domain. They are essential for email delivery and must be properly configured for your domain to receive emails.
Key Components:
- Priority: Lower numbers indicate higher priority mail servers
- Mail Server: The hostname of the mail server (must be a fully qualified domain name)
- TTL: Time To Live - how long the record should be cached
How MX Records Work:
- When someone sends an email to your domain, their mail server looks up your MX records
- The sending server tries to deliver to the highest priority (lowest number) server first
- If the primary server is unavailable, it tries the next priority server
- This process continues until the email is delivered or all servers fail
Best Practices:
- Use reasonable priorities such as 5 and 10 for primary and backup servers.
- Ensure mail servers have matching A records and PTR (rDNS) records.
- Monitor MX records after changing mail providers or servers.
Basic MX Record Configuration:
Popular Email Providers:
Google Workspace
Microsoft 365
No MX Records Found
The domain has no MX records configured. Emails will not be delivered.
Solution: Add MX records to your DNS configuration.
MX Points to CNAME
MX records should point to A records, not CNAME records.
Solution: Update MX to point to the actual hostname.
High TTL Values
Very high TTL values can delay email delivery during server changes.
Solution: Use reasonable TTL values (300-3600 seconds).
Single Point of Failure
Having only one MX record creates a single point of failure.
Solution: Configure backup MX records with higher priority numbers.
Incorrect Hostnames
MX must point to a valid, reachable mail server with a matching PTR record.
Solution: Verify the mail server hostname and configure matching A and PTR records.
Duplicate Priorities
Equal priorities can cause unstable routing between mail servers.
Solution: Assign distinct priority values to primary and backup servers.
How long does it take for MX changes to propagate?
MX record changes typically propagate within 24-48 hours, but can take up to 72 hours globally. The TTL value affects how quickly changes are recognized.
Can I have multiple MX records with the same priority?
Yes, multiple MX records can have the same priority. In this case, mail servers will randomly choose between them, providing load balancing.
What happens if all MX records are unreachable?
If all MX records are unreachable, the sending mail server will typically retry delivery for several days before returning the email as undeliverable.
Do I need MX records if I don't receive email?
If you don't want to receive email for a domain, you can either omit MX records entirely or set up a null MX record (priority 0, exchange ".") to explicitly reject email.
Can MX records point to IP addresses?
No, MX records must point to hostnames (A or AAAA records), not directly to IP addresses. This is required by RFC standards.
What does MX stand for?
Mail Exchange - a DNS record that routes email to your mail servers.
What does the priority number mean?
Lower numbers have higher priority and are tried first; others serve as backups.
Can a domain receive email without MX records?
No. Without MX records, sending servers cannot determine where to deliver email.
Related Tools
Need Help?
Our tools are designed to be intuitive, but if you need assistance, we're here to help.
About Our Tools
Professional-grade email and DNS diagnostic tools trusted by IT professionals worldwide.