This feature was working correctly for years. E-mails that had not been read would show with bold text in my inbox until I read them. Suddenly a few months ago they started showing as read immediately upon receipt. When I watch the messages coming in now I can see them show up as bold (unread) for a fraction of a second before they get marked as having been read. In an attempt to stop this from happening, I currently have the "Automatically mark messages as read" option turned off but it has not stopped the unwanted behavior. However, if I mark a message as "Unread" and then open that message it still shows as being "Unread" when I close the message, so the setting seems to be working somewhat.