Since a recent update, all my incoming email is marked as read. Went to Options > Options > Display and unchecked the "Automatically mark messages as read" box. Didn't help. Checked it again. Switched to "After displaying for 16 seconds" and unchecked the "Automatically mark messages as read" box again. Restarted Thunderbird. Messages still show as being read immediately after coming in. I hope someone can help with this. I miss important messages. Thanks.