mail.kiwi-backup.com has no CNAME records.
Question and response
Question
dig mail.kiwi-backup.com. NS
Answer
The response has no answer records.
Authority
kiwi-backup.com. 5586 SOA ns1.gandi.net. hostmaster.gandi.net. 1772064000 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0