Hi! None of the online comments, in either T-Bird Help, nor web searches, help with this problem, because the Settings interfaces are totally different from what are described in Help or in web searches. My new T-Bird update as of today, but also the preceding version, does not mark messages as read. Even after I have read a message it continues to be displayed as bold face after I move on to another. My only option is to left-click on the message, select MARK> on the drop-down, and select MARK AS READ. Nowhere in the setup or SETTINGS sections do I find the option: ___ Mark all opened messages as read or something like that ... which is what I need. Am I missing something? or is this a Bug? Many thanks for your reply ... tgk