mx1.risp.pl has no CNAME records.
Question and response
Question
dig mx1.risp.pl. NS
Answer
The response has no answer records.
Authority
risp.pl. 2827 SOA ns1.q3.pl. admin.q3.pl. 2020122800 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0