us6.oraclecloud.com has no MX records.
Question and response
Question
dig us6.oraclecloud.com. MX
Answer
The response has no answer records.
Authority
us6.oraclecloud.com. 600 SOA ns1.p201.dns.oraclecloud.net. hostmaster.oracle.com. 2026012102 7200 600 1209600 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0