As an Exchange administrator, you need to remain vigilant about every aspect of your users' mailboxes. One key task you need to perform regularly is auditing changes to mailbox folder and public folder permission to ensure no rogue user gains access to business-critical information.
Mailbox folder permission changes
Public folder permission changes
To audit folder permission changes:
Go to the Auditing tab.
Click the Advanced Audit Reports link.
View the reports under the Folder Access Permission Changes category.
Figure 1: Audit mailbox folder permission changes using Exchange Reporter Plus.