From time to time r2 may post important announcements within your Control Panel. This announcement would appear to you:
Immediately upon login into your Control Panel as a full page. After you have read the Announcement, you can click the Proceed button to continue working with your Control Panel.
Only once as a full page announcement. After you have seen the Announcement once, it would start appearing in the Announcement box, from where you can click on either its Title or Teaser line to view the complete announcement.
As an Archived Announcement from Help -> Announcements, after the Announcement has expired.