'''The Problem:''' When I view a message in the message pane after selecting the message with a single click I don't want the message to be marked as read automatically. But I want the message to be marked as read as soon as I double-click on it to open it in "full-view" in a new tab or window. I searched for this problem and found 2 older threads on the forum: * https://support.mozilla.org/de/questions/1144430 * https://support.mozilla.org/de/questions/1052712 There was no solution in those threads, so I did a little more research and finally found a working solution. But because those old threads were already archived I'm starting a new thread to provide the solution. '''The solution:''' When setting the following options you get the desired behavior: Options / Display / Advanced * Activate "Automatically mark messages as read". * Activate "After displaying for x seconds" and set the value to 999999 (which practically means "never"). So when you select a message (single click) and view it in the message pane the message won't be marked as read (unless you wait for more than 11 days). But when you open the message in a separate tab/window (double-click/enter) the message will be marked as read immediately.