mx.prod.qlmail.ch has no CNAME records.
Question and response
Question
dig mx.prod.qlmail.ch. NS
Answer
The response has no answer records.
Authority
prod.qlmail.ch. 7107 SOA . admin.qlns.ch. 2025072102 10800 3600 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0