smtp.coheris.cloud has no CNAME records.
Question and response
Question
dig smtp.coheris.cloud. NS
Answer
The response has no answer records.
Authority
coheris.cloud. 1634 SOA ns1.gandi.net. hostmaster.gandi.net. 1772064000 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0