ocus.nlb.efscloud.net has no MX records.
Question and response
Question
dig ocus.nlb.efscloud.net. MX
Answer
The response has no answer records.
Authority
ocus.nlb.efscloud.net. 300 SOA ns1.p201.dns.oraclecloud.net. hostmaster.ocus.nlb.efscloud.net. 7 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0