You are here: /bernle/exchange/pfdavadmin
Follow this link to download PFDAVAdmin.
When downloaded and extracted, you will find the following content:

Double Click on PFDAVAdmin.exe to launch the program:

On the File menu, select Connect and enter the hostname of your Exchange Server and Global Catalogue.
Make sure you select the "All Mailboxes" Radio Button, and press OK.

When connected, From the Tools menu, select Set Calendar Permissions

Press OK.

To select a user or group to give a certain permission to, select "Add":

In this example, we are going to browse for the group "Everyone". Select "Browse":

In the Drop Down Box, select your domain, and then double click the OU "Users" down below:

Select the group Everyone:

Press OK:

Make sure to change the Role to Reviewer, under Permissions, and hit OK:

Since we will not remove any existing permissions given, just hit OK:

Hit OK again:

A status bar will appear, showing the progress and result. When it´s finished close the dialog box and PFDAVAdmin and you´re done!
