mx.stemenno.com has no CNAME records.
Question and response
Question
dig mx.stemenno.com. NS
Answer
The response has no answer records.
Authority
stemenno.com. 3582 SOA dns.stemenno.com. hostmaster.stemenno.com. 1401409584 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0