Your first one is way to specific to be signaled by some kind of flags, the recipient might as well just read the subject line of your email if its well written.
But basically every e-mail client implements some kind of Priority/Importance header, that solves your problem. Nobody uses it though, and the few times someone decides to set "high priority" it might be in their opinion but not in mine. A more complex system won't see more adoption.
But basically every e-mail client implements some kind of Priority/Importance header, that solves your problem. Nobody uses it though, and the few times someone decides to set "high priority" it might be in their opinion but not in mine. A more complex system won't see more adoption.