mx.manjumohanmukherjee.com has no CNAME records.
Question and response
Question
dig mx.manjumohanmukherjee.com. NS
Answer
The response has no answer records.
Authority
manjumohanmukherjee.com. 3419 SOA dns.manjumohanmukherjee.com. hostmaster.manjumohanmukherjee.com. 1378079704 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0