This idea has been merged into another idea. To comment or vote on this idea, please visit APP-I-4738 Admins should be able to add portal users as subscribers to ideas.
Currently, you can only add watchers to a request if their name is in the user dropdown. However, watchers are added by email address if they vote on a request in the public board.
It would be nice to have the ability as an admin to add email addresses of users I know want to be watchers on a request, without requiring action on their part to vote the request