This plugin enables automatic e-mails to the relevant users during the collaboration workflow.
Unzip the peters_collaboration_emails folder to your WordPress plugins folder.
Details about the e-mails sent (who the sender should be; whether the contributor should know who approved his/her post; and so on) are configured in the Settings > Collaboration e-mails admin menu. The default settings should be sufficient for most implementations.
Moderator rules are also configured in the Settings > Collaboration e-mails admin menu. Moderators are Administrator or Editor users who should be notified whenever a post is submitted for review. You can create groups of Contributor users and assign different moderators for each group. In other words, different users can be notified based on who wrote a post. You can also assign moderators based on various taxonomies (such as tags, categories, and more) on post, pages, and custom post types. If a Contributor user belongs to multiple groups and/or a post has multiple taxonomy values, all moderators who have been assigned to the relevant groups or who match the post type rules are e-mailed.