Add non-members as watchers
It's a little annoying to have to add someone to a project in order to add them as a watcher on an issue, because they don't normally need to be on the project, they just need a reference to that one issue. So, there should be some way to add any user as a watcher of an issue. When you have a large organization, it's not practical to add everyone to a project just to be able to add them as watchers.
Redmine version 4.2.1.stable