We might be better off if conventions in email programs changed so that the "Send" was not the default but rather something like "Schedule this to be sent at th

We might be better off if conventions in email programs changed so that the "Send" was not the default but rather something like "Schedule this to be sent at the next top of the hour". We wouldn't have to resort to any UI fakery, and there might be interesting societal effects if widespread enough. (Most mail delivery doesn't need to be immediate, but pretty much no one tunes their setup to minimize interruptions.) It obviously won't work very well if it's entirely handled by the client, since your battery might die, you might go out of range, etc.