mail.ulimitserver.com has no MX records.
Question and response
Question
dig mail.ulimitserver.com. MX
Answer
The response has no answer records.
Authority
ulimitserver.com. 300 SOA ns1.ulimitserver.com. server.plus.hr. 2026022703 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0