Administrator Features:

• Enable / disable module
• Set the days till messages get deleted out of the database.
• Control access to access the messenger
• Control access to compose a new message
• Control access to reply to a message
• Put a message on your site so if a user is logged in they can see how many unread messages they have

User Features:

• Send a message to another user 
• Search for a username
• Reply to a message
• Forward a message
• Block users from sending you a message
• View your sent items
• Delete messages