mail.mizzoxinternal.pl has no CNAME records.
Question and response
Question
dig mail.mizzoxinternal.pl. NS
Answer
The response has no answer records.
Authority
mizzoxinternal.pl. 163 SOA jamie.ns.cloudflare.com. dns.cloudflare.com. 2395167857 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0