=== SenderHasMXRecord

Enable to validate that the sender of the email address domain name has a MX record advertised through DNS
that matches a supplied list of domains.

This is for instance useful when registering dynamically a public email service and ensure correct configuration
of the domain upon sending and mitigate some identity spoofing attempts on a publicly accessible platform allowing
dynamic domain registration.

Example:

....
<mailet match="SenderHasMXRecord=mx.apache.org" class="any-class"/>
....