nagios4.hoster.kz has no MX records.
Question and response
Question
dig nagios4.hoster.kz. MX
Answer
The response has no answer records.
Authority
hoster.kz. 136 SOA ns3.hoster.kz. support.hoster.kz. 2026022601 3600 3600 1360000 136
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0