EnvelopeMessages is a core component of Joomla and a built-in private messaging system for backend users. It allows you to send and receive messages to other users with permission to access the administrator area.

The messaging component is very easy to use; however, users often forget the possibility to configure the component in Components - Messages - My Settings. You can configure the system to email you every new message, delete them after an x amount of days, and you can also lock your inbox.