mail.pbw.pl has no MX records.
Question and response
Question
dig www.pbw.pl. MX
Answer
The response has no answer records.
Authority
pbw.pl. 3600 SOA ns1.premium.pl. admin.premium.pl. 918294251 14400 7200 2419200 3600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0