mx1.privateemail.com has no NS records.
NS records for this zone are defined at privateemail.com.
NS records for this zone are defined at privateemail.com.
Question and response
Question
dig mx1.privateemail.com. NS
Answer
The response has no answer records.
Authority
privateemail.com. 3600 SOA edns.registrar-servers.com. support.namecheap.com. 1769091243 43200 3600 1209601 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0