smtp.mailrcld.com has no CNAME records.
Question and response
Question
dig smtp.mailrcld.com. NS
Answer
The response has no answer records.
Authority
mailrcld.com. 971 SOA pns31.cloudns.net. support.cloudns.net. 2026021601 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0