potpis.carnet.hr has no MX records.
Question and response
Question
dig potpis.carnet.hr. MX
Answer
The response has no answer records.
Authority
carnet.hr. 600 SOA dns1.carnet.hr. hostmaster.carnet.hr. 2026022601 10800 3600 2419200 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0