mrf.host.nask.pl has no MX records.
Question and response
Question
dig mrf.host.nask.pl. MX
Answer
The response has no answer records.
Authority
host.nask.pl. 120 SOA ns.nask.org.pl. dns.nask.pl. 2026021600 28800 3600 2592000 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0