Administrators can now invite and add guest users to your Forest account. Guest users can't be given admin privileges, but instead, they can access and contribute to specific content (i.e. ideas, campaigns, portfolios, custom pages, or evaluations) they are assigned to. You'll see a "Guest User" label next to a user's name for all content they are added to.
How to add/invite a Guest User your Forest account:
How Guest Users setup their Forest account through the email invite:
How add a Guest User access to a piece of content:
How to remove a Guest User from a piece of content:
How to delete a Guest User from your Forest account: