mail1.edu.sk has no MX records.
Question and response
Question
dig mail1.edu.sk. MX
Answer
The response has no answer records.
Authority
edu.sk. 86400 SOA ns.telecom.sk. hostmaster.telecom.sk. 2025100209 28800 3600 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0