proxy.api-mail.com has no CNAME records.
Question and response
Question
dig proxy.api-mail.com. NS
Answer
The response has no answer records.
Authority
api-mail.com. 583 SOA ns73.domaincontrol.com. dns.jomax.net. 2026022513 28800 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0