mx0129.ppsmtp.com has no CNAME records.
Question and response
Question
dig mx0129.ppsmtp.com. NS
Answer
The response has no answer records.
Authority
ppsmtp.com. 1800 SOA ns1.p68.dns.oraclecloud.net. hostmaster.ppsmtp.com. 291 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0