Apex domains cannot have CNAME records.
Question and response
Question
dig upsemail.com. NS
Answer
upsemail.com. 5 NS nsa.ups.com.
upsemail.com. 5 NS auth1.dns.cogentco.com.
upsemail.com. 5 NS cbru.br.ns.els-gms.att.net.
upsemail.com. 5 NS cmtu.mt.ns.els-gms.att.net.
upsemail.com. 5 NS nsb.ups.com.
upsemail.com. 5 NS auth2.dns.cogentco.com.
Authority
The response has no authority records.
Additional
nsa.ups.com. 5 A 153.2.242.115
nsb.ups.com. 5 A 153.2.244.155
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0