SharingItem.Permission Property (Outlook)
The Permission property should be synchronized with the PermissionTemplateGuid property to accurately reflect the permission status of the SharingItem. Setting the PermissionTemplateGuid property to a valid GUID should also incur setting the Permission property to OlPermission.olPermissionTemplate.
When no Information Rights Management (IRM) has been set up (in which case the Permission property is OlPermission.olUnrestricted), or the restriction is not to forward the SharingItem (in which case the Permission property is OlPermission.olDoNotForward), the value of the PermissionTemplateGuid property should be an empty string.
Although you can view content that is protected by IRM on any computer running the 2007 Microsoft Office system or a later version, you must have Microsoft Office Professional Edition 2003, Microsoft Office Outlook 2007, or a later version of Outlook to create or send an e-mail that is protected by IRM.