If you're like me, then you like to keep both your personal and work appointments/tasks in Outlook, and you would prefer all your appointments to be marked as private, unless you explicitly wish to share it with the colleagues on the same Exchange network as you.
Here's how! First we make a new Outlook appointment form, based on the standard form:
Open up Outlook
Go to the "Tools Menu"
Select the "Forms" option
Select "Design a Form..."
Select "Look in: Standard Form Library"
Choose "Appointment" from the list
Press the "Open" button (or double click "Appointment")
Select the "(All Fields)" tab
Choose "Select From: All Appointment Fields"
Scroll down until you find "Sensitivity", which is set to "Normal" by default.
Change the "Sensitivity" setting from "Normal" to "Private"
Push the "Publish" button on the toolbar, followed by "Publish Form"
Enter "AppointmentPrivate" as your "Display Name:"
Push the "Publish" button
Next, we want to tell Outlook to use this new form whenever we create new appointments:
In the main Outlook user interface;
Select your Folder List
Right click your calendar
Switch to the "General" tab
Choose "PrivateAppointment" from the "When posting to this folder, use:" drop-down
Push the "OK" button.
All done! Now, whenever you create a new appointment, you should see that the private icon (a padlock) is highlighted. Note that your colleagues will still be able to see that you have an appointment, but they just wont know what it is, or any of the details such as title or content. If you ever want to make an appointment public, you can simply unhighlight the privacy icon.