mail.vh.pl has no CNAME records.
Question and response
Question
dig mail.vh.pl. NS
Answer
The response has no answer records.
Authority
vh.pl. 6125 SOA ns1.vh.pl. biuro.vh.pl. 2025102401 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0