DNS
MX Record
Mail Exchange record. A DNS record specifying the mail server responsible for receiving email for a domain.
Definition
An MX (Mail Exchange) record is a DNS record that specifies which mail server is responsible for receiving email on behalf of a domain. MX records include a priority value - lower numbers indicate higher priority. When sending email, the sender's server queries MX records to determine where to deliver the message. Missing or incorrect MX records prevent email delivery.
Examples
example.com MX 10 mail.example.comexample.com MX 20 mail2.example.com (backup)
Pro Tip
Always have at least two MX records with different priorities for redundancy.