webmail.corehrmail.com has no CNAME records.
Question and response
Question
dig webmail.corehrmail.com. NS
Answer
The response has no answer records.
Authority
corehrmail.com. 75 SOA leonidas.ns.cloudflare.com. dns.cloudflare.com. 2397260474 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0