cust.stratogen.net has no MX records.
Question and response
Question
dig cust.stratogen.net. MX
Answer
The response has no answer records.
Authority
cust.stratogen.net. 1800 SOA buck.ns.cloudflare.com. dns.cloudflare.com. 2392892919 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0