MX records, also known as Mail Exchange records, are DNS (Domain Name System) records that specify the mail server(s) responsible for handling email messages for a domain name. In simpler terms, an MX record is like an address book entry for email servers.
When someone sends an email to an email address, their email client uses the recipient’s domain name to look up the MX records for that domain. The MX records then specify the mail servers that are responsible for receiving and delivering the email messages to the recipient’s inbox.
MX records have a priority value that indicates the order in which email servers should be used. When multiple MX records are present for a domain, the email client first tries to send the email to the server with the highest priority (lowest numerical value), and if that server is unavailable, it tries the server with the next highest priority, and so on.
For example, if the MX records for a domain are set up like this:
example.com. IN MX 10 mail1.example.com.
example.com. IN MX 20 mail2.example.com.An email client will first try to send email to mail1.example.com, as it has the higher priority value of 10. If that server is unavailable, the email client will try to send the email to mail2.example.com.
MX records are an important part of email delivery, and they can be configured and managed using the domain name system (DNS) settings for a particular domain.