backupproxy2-pub.mail.unifiedlayer.com has no MX records.
Question and response
Question
dig backupproxy2-pub.mail.unifiedlayer.com. MX
Answer
The response has no answer records.
Authority
mail.unifiedlayer.com. 300 SOA ns1.unifiedlayer.com. root.unifiedlayer.com. 2021072800 28800 14400 3600000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0