To manually install Protective Markings on Outlook for a Mac you first need an addin manifest file. Preemptive will either provide you with a demonstration manifest file, or one customised for your organisation.

Once you have the file, follow the procedures below to deploy the addin.

Open Outlook.

On the toolbar click on the Get Add-ins button.

In the left hand navigator click on "My Add-ins"

Click on Add a custom add-in, Add from file.

Select the manifest file provided, click Open

You're done.

Now when you send an email you should be prompted to select a Protective Marking.