mailer.fluidparty.com has no CNAME records.
Question and response
Question
dig mailer.fluidparty.com. NS
Answer
The response has no answer records.
Authority
fluidparty.com. 5066 SOA ns11.infomaniak.ch. hostmaster.infomaniak.ch. 2025090608 10800 3600 605800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0