mx.lucentharbor.com has no CNAME records.
Question and response
Question
dig mx.lucentharbor.com. NS
Answer
The response has no answer records.
Authority
lucentharbor.com. 3431 SOA dns.lucentharbor.com. hostmaster.lucentharbor.com. 1225970125 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0