Please implement a clickable green checkmark option (or something similar) for completed emails. Ideally this checkbox status would display for all emails and would appear next to the mini-icons (trash, archive, move, etc). Many of us never delete emails and simply archive them. However, when we use the "All Mail" folder, it would be helpful if we could have an option to select a checkmark to know that we have completed that particular email or thread as it would help visually with quickly identifying which emails require attention and which have already been dealt with. (Similar to Outlook's checkmark option) Thanks!