ntp.vdx.sh has no MX records.
Question and response
Question
dig ntp.vdx.sh. MX
Answer
The response has no answer records.
Authority
vdx.sh. 1800 SOA dean.ns.cloudflare.com. dns.cloudflare.com. 2397419458 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0