smtp2.oxemis.com has no CNAME records.
Question and response
Question
dig smtp2.oxemis.com. NS
Answer
The response has no answer records.
Authority
oxemis.com. 8204 SOA ns.oxemis.com. webmaster.oxemis.com. 2025101601 10800 3600 1209600 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0