MX Record Checker
Look up mail exchange (MX) records for any domain.
Enter a domain name or email address. The @ prefix will be stripped automatically.
What Are MX Records?
MX (Mail Exchange) records are a type of DNS record that specifies which mail servers are responsible for receiving email on behalf of a domain. When someone sends an email to user@example.com, the sending mail server queries DNS for the MX records of example.com to determine where to deliver the message. Without properly configured MX records, email cannot be delivered to a domain.
Understanding MX Priority Values
Each MX record has a priority value (also called preference). Lower numbers indicate higher priority — a mail server with priority 10 will be tried before one with priority 20. This system enables redundancy: if the primary mail server is unavailable, the sending server will attempt delivery to the next-highest-priority server. Many domains use multiple MX records with different priorities to ensure email delivery even during outages.
How to Diagnose Email Delivery Issues
When email is not being delivered to a domain, checking MX records is one of the first diagnostic steps. Common issues include missing MX records, records pointing to decommissioned servers, incorrect priority values causing mail to route to the wrong server, and MX hostnames that do not resolve to valid IP addresses. If an MX record's hostname cannot be resolved to an A record, mail servers will be unable to connect and delivery will fail.
Common Mail Providers
You can often identify a domain's email provider by examining its MX records. Google Workspace domains typically point to servers like aspmx.l.google.com. Microsoft 365 domains use hostnames ending in mail.protection.outlook.com. Domains using Proton Mail, Zoho, Fastmail, or other providers each have distinctive MX hostnames. This information is useful for IT administrators migrating email services or verifying that DNS changes have propagated correctly.