_spf.nask.pl has no MX records.
Question and response
Question
dig _spf.nask.pl. MX
Answer
The response has no answer records.
Authority
nask.pl. 600 SOA ns.nask.org.pl. dns.nask.pl. 2026021900 21600 3600 1209600 21600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0