mx.cantermore.com has no CNAME records.
Question and response
Question
dig mx.cantermore.com. NS
Answer
The response has no answer records.
Authority
cantermore.com. 600 SOA authns1.rackanddata.com. domainadmin.rackanddata.com. 1363453948 600 300 3600 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0