mx.playmobile.pl has no CNAME records.
Question and response
Question
dig mx.playmobile.pl. NS
Answer
The response has no answer records.
Authority
playmobile.pl. 60 SOA ns1.project4.pl. dnsmaster.project4.pl. 2026022302 7200 3600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0