ns1.3s.pl has no MX records.
Question and response
Question
dig ns1.3s.pl. MX
Answer
The response has no answer records.
Authority
3s.pl. 360 SOA ns1.3s.pl. hostmaster.3s.pl. 2025122200 10800 3600 1814400 360
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0