smtp.hctc.com has no MX records.
Question and response
Question
dig smtp.hctc.com. MX
Answer
The response has no answer records.
Authority
hctc.com. 600 SOA mailbe.hcc.net. hostmaster.hcc.net. 2015092870 600 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0