Last week I wrote about Organic Groups in Drupal and how to customize the way it controls access to content. This article describes how you can use the Rules module to create a custom, lightweight solution for sending email notifications to members of a group whenever new content is added.
The Organic Groups module in Drupal provides groups of users with a way of discussing common interests in a separate space of their own. It does a great job at controlling who has access to what, depending on how open you want your groups to be. Yet, we've found in a couple of projects that it didn't quite fulfill our needs. Naturally, you wouldn't be reading this if we hadn't found a solution.