The Messages tool allows users to send and receive private messages to other site participants.

By default, users may send messages to one or more individual participants.  Users may also send messages to all members of a particular group, all participants in a particular role, or all participants in the site.

The Messages tool is site-specific; messages may be sent only to users in the site in which they are composed, and they may be viewed only in the site in which they are composed and received.  

Note: For instructions on how to add this or any other tool to your site, see How do I add tools to my site?