mail.engine.anexia-it.com has no CNAME records.
Question and response
Question
dig mail.engine.anexia-it.com. NS
Answer
The response has no answer records.
Authority
anexia-it.com. 1047 SOA acns02.xaas.systems. support.anexia.at. 252 10000 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0