union.hcc.net has no MX records.
Question and response
Question
dig union.hcc.net. MX
Answer
The response has no answer records.
Authority
hcc.net. 600 SOA mailbe.hcc.net. hostmaster.hcc.net. 2018041095 600 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0