ns1.9t4.net has no MX records.
Question and response
Question
dig ns1.9t4.net. MX
Answer
The response has no answer records.
Authority
9t4.net. 1800 SOA ns.gransy.com. root.gransy.com. 2769544720 86400 900 1209600 1800
ns1.9t4.net. 1800 NSEC ns2.9t4.net. A AAAA RRSIG NSEC
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0