mx2.cityemail.com has no NS records.
NS records for this zone are defined at cityemail.com.
NS records for this zone are defined at cityemail.com.
Question and response
Question
dig mx2.cityemail.com. NS
Answer
The response has no answer records.
Authority
cityemail.com. 3600 SOA ns1.linuxmagic.com. hostmaster.wizard.ca. 408 21600 3600 604800 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0