ns02.ndacorp.com has no MX records.
Question and response
Question
dig ns02.ndacorp.com. MX
Answer
The response has no answer records.
Authority
ndacorp.com. 38400 SOA ns02.ndacorp.com. twang.ndacorp.com. 2013051592 10800 3600 604800 38400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0