mx.nask.net.pl has no MX records.
Question and response
Question
dig mx.nask.net.pl. MX
Answer
The response has no answer records.
Authority
nask.net.pl. 3600 SOA ns.nask.org.pl. dns.nask.pl. 2025122900 28800 3600 604800 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0