ns4.sk.eserver.net has no MX records.
Question and response
Question
dig ns4.sk.eserver.net. MX
Answer
The response has no answer records.
Authority
sk.eserver.net. 1800 SOA ns1.eserver.net. hostmaster.eserver.sk. 2025102801 7200 3600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0