The Privatemsg module enables private messages to be sent from one user to another.

1. Enable the module. Click administer » modules and check the box next to privatemsg.
2. Give the permissions to the appropriate user group (role). Click administer » users » configure tab » permissions and check the box next to access private messages for the roles you wish to grant the permission to.
3. Click administer » settings » privatemsg.
4. Select a minimum amount of time between messages. This will cut down on abuse of the private message system.
5. Select whether you want users to see if the message they've sent has been read.
6. Select the number of message per page.
7. Select whether you want "Write to author" links appear below other users' main content and below other users' comments.
8. Click the "Save configuration" button.