mail.e-b.be has no CNAME records.
Question and response
Question
dig mail.e-b.be. NS
Answer
The response has no answer records.
Authority
e-b.be. 600 SOA ns1.ebusiness.be. dns.ebusiness.be. 2019100901 10800 3600 604801 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0