email.active24.com has no CNAME records.
Question and response
Question
dig email.active24.com. NS
Answer
The response has no answer records.
Authority
active24.com. 3600 SOA alfa.ns.active24.cz. hostmaster.active24.cz. 2025110406 10800 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0