zrh1.oracleemaildelivery.com has no MX records.
Question and response
Question
dig zrh1.oracleemaildelivery.com. MX
Answer
The response has no answer records.
Authority
zrh1.oracleemaildelivery.com. 300 SOA ns1.p68.dns.oraclecloud.net. hostmaster.zrh1.oracleemaildelivery.com. 726859 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0