_acme-challenge.ocus.efscloud.net has no MX records.
Question and response
Question
dig acme-challenge.efscloud.net. MX
Answer
The response has no answer records.
Authority
acme-challenge.efscloud.net. 30 SOA ns3.efscloud.net. root.efscloud.net. 4745 86400 7200 3600000 30
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0