mx1.inetia.pl has no CNAME records.
Question and response
Question
dig mx1.inetia.pl. NS
Answer
The response has no answer records.
Authority
inetia.pl. 5256 SOA chacha.inetia.pl. hostmaster.inetia.pl. 2026022305 691200 7200 2419200 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0