relay-mx.servercentral.com has no MX records.
Question and response
Question
dig relay-mx.servercentral.com. MX
Answer
The response has no answer records.
Authority
servercentral.com. 600 SOA ns1.servercentral.net. dns.servercentral.net. 2025110302 600 600 600 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0