mx.eigbox.net has no CNAME records.
Question and response
Question
dig mx.eigbox.net. NS
Answer
The response has no answer records.
Authority
eigbox.net. 3600 SOA ns1.yourhostingaccount.com. admin.yourhostingaccount.com. 2007092701 10800 3600 608400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0