stackpathdns.net has no MX records.
Question and response
Question
dig stackpathdns.net. MX
Answer
The response has no answer records.
Authority
stackpathdns.net. 1800 SOA noel.ns.cloudflare.com. dns.cloudflare.com. 2396985716 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0