What is an MX record? (Email glossary definition)

MX record (Mail Exchange record) is a DNS entry that specifies the mail server(s) responsible for receiving email on behalf of a domain. It is the email equivalent of a postal address. It tells the rest of the internet "send email for this domain to that server."

A domain can have multiple MX records with different priority values. Lower priority numbers win. Receivers attempt the lowest-priority server first and fall back to higher priorities if the primary is unreachable.

A typical lookup looks like:

yourdomain.com  IN  MX  10  mx1.yourdomain.com.
yourdomain.com  IN  MX  20  mx2.yourdomain.com.

For email verification: an address on a domain with no MX records cannot receive mail, regardless of how legitimate the address itself looks. Step 3 of our 11-step verification engine checks for MX records. Failure returns invalid.

Common configurations: Google Workspace publishes specific MX records pointing at Google's mail infrastructure. Microsoft 365 uses Microsoft's. Small businesses typically use their hosting provider's mail server or third-party providers like Zoho.