mail.mpcustomer.com has no CNAME records.
Question and response
Question
dig mail.mpcustomer.com. NS
Answer
The response has no answer records.
Authority
mpcustomer.com. 600 SOA ns1.midphase.com. hostmaster.westdc.net. 2026021103 86400 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0