Most email admins would agree managing Exchange Public Folder permissions can be a painful experience especially if you have a large organization.  Microsoft released a tool a few years ago called PFDAVadmin, or the Exchange Server Public Folder Distributed Authoring and Versioning-based Administration tool.  Initial releases of this tool allowed you to manage the permissions on public folders. The beauty here is that you are able to manipulate a permission and then propagate it down to an individual sub-folder, or all sub-folders.  This was invaluable when you are working at the root level and needed to push a mass permission down the tree.  Even better, the latest release of this tool allows you to now manage permissions against Exchange mailboxes in the same manner.  The tool also does a DACL (Discretionary Access Control List) state check.  It can also be told to fix all existing DACL's on the fly.  Things such as unresolved SIDs and missing default (anonymous) permissions can be fixed instantaneously, hundreds in only a few seconds.  We have found this fixes all kinds of public folder\client related issues.  The tool can be fetched from Microsoft here.

Here you can determine the permissions, DACL state and item level permissions.