Course messages are private and secure text-based communication that occurs within a course and among course members. Although similar to email, you must be logged into a course to read and send course messages.
Before Service Pack (SP) 14, the only way to know if you had any new course messages was to constantly log in to your course and check. In SP 14, course messages are part of the notifications framework. Anyone enrolled in a course can receive notification that they have new messages from the Updates area in My Blackboard, in the What's New module on both institutional and course module pages, and from email. Users can manage their notification settings to include course messages and set preferences.
Notifications includes organization messages as well.