Apex domains cannot have CNAME records.
Question and response
Question
dig sendsmaily.info. NS
Answer
sendsmaily.info. 5 NS ns-893.awsdns-47.net.
sendsmaily.info. 5 NS ns-467.awsdns-58.com.
sendsmaily.info. 5 NS ns-1624.awsdns-11.co.uk.
sendsmaily.info. 5 NS ns-1160.awsdns-17.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0