When logged into web administration as a SYSADMIN, the Usage page is missing processor and memory usage for the mail services. Normally you can monitor the percentage processor time and memory usage each mail service uses.
This is caused by the Process performance counters being disabled in Windows. You can confirm this by running Perfmon and seeing whether you can monitor any Process.
You can enable the counters by running Regedit, and setting the following registry value to be 0. After changing this registry value you will need to cycle the MailEnableAppPool application pool under IIS.
Disable Performance Counters = 0
|Class:||PRB: Product Problem or Issue|
|Revised:||Friday, March 16, 2018|