mx1.privateemail.com has no CNAME records.
Question and response
Question
dig mx1.privateemail.com. NS
Answer
The response has no answer records.
Authority
privateemail.com. 2949 SOA edns.registrar-servers.com. support.namecheap.com. 1769091243 43200 3600 1209601 3601
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0