arn1.oracleemaildelivery.com has no MX records.
Question and response
Question
dig arn1.oracleemaildelivery.com. MX
Answer
The response has no answer records.
Authority
arn1.oracleemaildelivery.com. 300 SOA ns1.p68.dns.oraclecloud.net. hostmaster.arn1.oracleemaildelivery.com. 694637 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0