MX.fusemail.net has no CNAME records.
Question and response
Question
dig MX.fusemail.net. NS
Answer
The response has no answer records.
Authority
fusemail.net. 2540 SOA ns1.electric.net. dns.electric.net. 1457392698 10000 1800 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0