We currently have 3 servers running the CAS role that report the Compliance\ComplianceOutlookLogonToArchiveRpcCtpMonitor as Unhealthy after the CU9. What does this monitor check and considering there is no Exchange archiving in the environment, is this safe to ignore?

Hi Mike,

Please check if there is any related event log in exchange server, if no related logs and no exchange archiving, you can ignore it safely.

In addition, I also recommend you refer to the following article to understand how to troubleshoot this kind of issue:

Exchange 2013 Managed Availability HealthSet Troubleshooting

Best regards,