mail.yomabox.eu has no CNAME records.
Question and response
Question
dig mail.yomabox.eu. NS
Answer
The response has no answer records.
Authority
yomabox.eu. 99 SOA dns200.anycast.me. tech.ovh.net. 2026020400 86400 3600 36000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0