In a roster for a group, there are two options when sending messages. One is to send an Inbox message, while the other is Send Via E-Mail.
Inbox messages allow users to message one another behind the password. This means the user must log in to send and receive messages. Messages that are sent can be accessed by a user in the Messages link at the top of the screen when the user is logged in.
Send Via E-mail allows the users to send a message directly to an E-mail address a user has in the system. The user will receive the message in their E-mail inbox rather than in the Messages section of the software. Users can reply through the E-mail to one another, but not back into the Messages inside the system.