Free MX Lookup Tool
Free MX lookup tool — find mail servers, check MX record priorities, and identify email providers for any domain. Instant results, no install required.
What Are MX Records?
MX (Mail Exchange) records are DNS records that specify which mail servers are responsible for accepting email for a domain. Each MX record contains a priority value and a mail server hostname.
When an email is sent to an address at a domain, the sending server queries DNS for that domain's MX records and attempts delivery to the server with the lowest priority number first. If that server is unavailable, it falls back to higher-numbered servers.
How MX Priority Works
MX priority values determine the order in which mail servers are contacted. A domain with records at priority 10 and 20 will receive mail at the priority-10 server first, with the priority-20 server acting as a backup.
Multiple MX records with the same priority enable round-robin load balancing. This is common with large providers like Google Workspace and Microsoft 365, which distribute email across several servers at the same priority level.
Identifying Email Providers from MX Records
You can determine which email service a domain uses by examining its MX record hostnames. Google Workspace uses aspmx.l.google.com, Microsoft 365 uses *.mail.protection.outlook.com, Amazon SES uses inbound-smtp.*.amazonaws.com, and Zoho Mail uses mx.zoho.com.
This information is useful for IT administrators, security researchers, and anyone who needs to understand a domain's email infrastructure.
Run a Free MX Lookup
Enter any domain above to instantly retrieve its MX records, priority values, and detected email provider. Results include TTL values and server reachability status — no command-line tools or software installation needed.
Need more than MX? After running your lookup, explore related tools like the SPF Record Checker to verify email sender authorization, the DMARC Checker for authentication policy analysis, or the full Email Security Checker for a comprehensive audit.
Frequently Asked Questions
What is an MX record and why do I need it?
An MX (Mail Exchange) record is a DNS record that directs email to the correct mail server for your domain. Without MX records, email sent to your domain cannot be delivered. Every domain that needs to receive email must have at least one MX record pointing to a valid mail server.
How many MX records can a domain have?
A domain can have as many MX records as needed, though most domains use between 2 and 5. Multiple MX records provide redundancy — if the primary server is unavailable, email is routed to backup servers based on priority values. Lower priority numbers indicate preferred servers.
How do I know if my MX records are set up correctly?
Correctly configured MX records should point to valid, reachable mail server hostnames (not IP addresses). Each record needs a priority value, and the target servers must accept email connections on port 25. Use this MX lookup tool to check your MX records and verify they resolve to working mail servers.
What happens if I don't have MX records?
Without MX records, sending mail servers have no way to determine where to deliver email for your domain. Most email will bounce back to the sender with a "no MX record" or "host not found" error. Some older servers may fall back to the domain's A record, but this behavior is unreliable and not recommended.
How long does it take for MX record changes to take effect?
MX record changes propagate based on the TTL (Time To Live) value set on the record. Most DNS providers set TTLs between 300 seconds (5 minutes) and 86400 seconds (24 hours). After updating MX records, full propagation across all DNS resolvers worldwide typically completes within 24–48 hours, though most resolvers see the change much sooner.