smtp.private.onappcdn.com has no MX records.
Question and response
Question
dig smtp.private.onappcdn.com. MX
Answer
The response has no answer records.
Authority
onappcdn.com. 3600 SOA dns41.cloudns.net. noc.virtuozzo.com. 2026021102 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0