smtp.mynet.com.pl has no MX records.
Question and response
Question
dig smtp.mynet.com.pl. MX
Answer
The response has no answer records.
Authority
mynet.com.pl. 600 SOA ns1.mynet.com.pl. dns.mynet.com.pl. 2024102902 86400 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0