A couple of thoughts...
When a user joins a project (or any other listing), they are presented with an option to receive notifications. Currently this allows for "Tools" users to send that user monthly email blasts and such. That option setting could be expanded to also allow the user to choose to receive the project's activity stream.
Now, once the user has elected to receive the activity stream for a project, the stream can generate a lot of messages. So there might be an option to limit the number of emails to a few times a day instead of per activity.
The application already sends emails to users when a user is assigned a ticket, assigned a task, or invited to a project. There is a general capability for a user to subscribe to all discussion topics -- that feature is not currently exposed in the user interface for users, but an admin can turn that on. Additionally, administrative users receive notifications on new listings.
On an intranet, I always turn on the notification capability to receive all discussion messages, new ideas, and more.
So, we need a few more thought around enabling notifications for all users.
- Where should the feature be enabled?
- What should the emails look like?
etc.