mx.artemis-bm.com has no CNAME records.
Question and response
Question
dig mx.artemis-bm.com. NS
Answer
The response has no answer records.
Authority
artemis-bm.com. 2234 SOA dns.artemis-bm.com. hostmaster.artemis-bm.com. 1645678907 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0