ntp01.pingless.com has no MX records.
Question and response
Question
dig ntp01.pingless.com. MX
Answer
The response has no answer records.
Authority
pingless.com. 1800 SOA charles.ns.cloudflare.com. dns.cloudflare.com. 2396003446 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0