smtp.spoje.net has no CNAME records.
Question and response
Question
dig smtp.spoje.net. NS
Answer
The response has no answer records.
Authority
spoje.net. 3600 SOA ns.spoje.net. tech.spoje.net. 1772474503 3600 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0