mx.dynamail.ch has no CNAME records.
Question and response
Question
dig mx.dynamail.ch. NS
Answer
The response has no answer records.
Authority
dynamail.ch. 3575 SOA ns1.dynanet.ch. hostmaster.dynanet.ch. 2025105930 86400 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0