smtp.slovanet.sk has no MX records.
Question and response
Question
dig smtp.slovanet.sk. MX
Answer
The response has no answer records.
Authority
slovanet.sk. 10800 SOA ns.slovanet.net. dns.slovanet.net. 2026022502 7200 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0