smtp.accountorcloud.com has no CNAME records.
Question and response
Question
dig smtp.accountorcloud.com. NS
Answer
The response has no answer records.
Authority
accountorcloud.com. 300 SOA udns1.cscdns.net. premiumdns.support.neustar. 2020021995 3600 3600 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0