How can the errors be logged and tracked when a service request is not created through email?

If an email is received by Oracle Engagement Cloud but fails to create a service request due to validation issues on the SR, or for another reason, the failure is captured in the InboundMessage object.

Go to Service Infolets > Inbound Messages to see if a failure occurred. To see the reason for the failure, export the data from the Inbound Messages object, then check the StatusDetails attribute which shows the reason of the failure.