Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain smtp.email.us-phoenix-1.ocs.oraclecloud.com is not the root of its zone.
Instead, try zone transfer on us-phoenix-1.ocs.oraclecloud.com .
Instead, try zone transfer on us-phoenix-1.ocs.oraclecloud.com .