This could work okay at places where there's a pretty standard set of working hours for most everyone. If you're the kind of place that runs basically 8AM to 5PM and almost everyone tends to work something pretty close to inside that kind of schedule, it wouldn't be hard to not email folks when they're off. You could just limit to only emailing between 8 and 5. But in a lot of work places, it's not that simple. Like my husband's plant works several shifts. There are lots of people working lots of different schedules. What would be normal working hours for some bosses and employees to email are likely to be intrusive for others. Like his email will sometimes blow up around when the shift that's at work at 4AM is having a meeting. If he was also at work at 4AM, it would be no biggie, but since he doesn't start till 7, it is a nuisance that wakes us up while we're sleeping if we leave the phone turned on. And he deals with people in different plants in different time zones, even different countries,too, so it would be a challenge to make sure that not only are the emails matching up with that employee's normal work schedule, but also to make that schedule work with the time differences. To email someone who's working in the plant in China would require being awake at a time that is definitely not a typical working time for the people in the central time zone of the US where we live.