mail.core.icm.edu.pl has no MX records.
Question and response
Question
dig mail.core.icm.edu.pl. MX
Answer
The response has no answer records.
Authority
core.icm.edu.pl. 3600 SOA ns1.net.icm.edu.pl. hostmaster.core.icm.edu.pl. 2025102901 28800 7200 1814400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0