mail57.dopplermta9.com has no MX records.
Question and response
Question
dig mail57.dopplermta9.com. MX
Answer
The response has no answer records.
Authority
dopplermta9.com. 600 SOA pdns13.domaincontrol.com. dns.jomax.net. 2025121704 28800 7200 604800 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0