I'm curious if there's a way to deactivate the feature/behavior in Mac Mail (Sierra) where mail is automatically marked as read when clicked (I want it to remain unread until I click otherwise). I know that I can use the "Classic View" to remove the preview feature, but that doesn't accomplish what I'm aiming for (I want the preview to remain active). And I know there used to be a plugin called TruePreview which offered this feature, but it's no longer available. Any ideas?
"Mail Act-On" by SmallCubed has a feature to "Do not mark message as read". It currently costs $30 and that is a lot if that is the only feature you plan to use (it's main purpose is to help you create advanced mail processing rules). I have used it in the past and it worked well (currently using Outlook).