mail.ibrowse.com has no CNAME records.
Question and response
Question
dig mail.ibrowse.com. NS
Answer
The response has no answer records.
Authority
ibrowse.com. 10800 SOA ns1.domaindiscount24.net. tech.key-systems.net. 2026021203 10800 3600 604800 28800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0