It's amazing the importance one little function, such as "mark as unread", can have on a daily routine. Quite simply, I would be lost without it. I wouldn't stand a chance at maintaining a job that requires even the smallest amount of communication via email.
The only thing I can imagine that would be any better is a "mark as unheard" device. This tool sends a signal to another person's brain that tells them to repeat whatever they just said, at a given time. I actually already have this device created, but I can't sell it. The government is all up in arms over its mind controlling abilities for some reason.
I am under the impression, however, that they stole my creation and are using it as we speak. They're transmitting its signal over FM radio, specifically on Top 40 channels. It's the only possible explanation as to why millions continue to re-listen to the likes of Justin Bieber.
Baby, baby, baby, ooh
Baby, baby, baby, noo!