spf_r.oracle.com has no MX records.
Question and response
Question
dig spf_r.oracle.com. MX
Answer
The response has no answer records.
Authority
oracle.com. 900 SOA ns1.p201.dns.oraclecloud.net. hostmaster.oracle.com. 2026022201 7200 600 1209600 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0