Redmine

Hi, we're still new using Redmine, and we use it to handle our internal projects.

We are set up in a way that an admin assigns an issue to a developper, and the end client is added as an observer so that he knows when a task has started and when it's finished. The problem is that the observer (the client) ends up receiving a ton of notification emails...

We would like to set it up so that an observer receives notifications ONLY when an issue has been started to be worked on (In Progress) and when it's closed.

Is that possible? If so, how do we set that up?

Thanks in advance,
Jeremy