smtp.secureserver.net has no MX records.
Question and response
Question
dig smtp.secureserver.net. MX
Answer
The response has no answer records.
Authority
smtp.secureserver.net. 3600 SOA cns3.secureserver.net. dns.jomax.net. 2024040200 300 600 1209600 3600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0