mailsenders.netsuite.com has no CNAME records.
Question and response
Question
dig mailsenders.netsuite.com. NS
Answer
The response has no answer records.
Authority
netsuite.com. 600 SOA a1-124.akam.net. dnsadmin.nsgbu.internal. 2602271345 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0