How is this possibly beneficial? My dealing with email after 6PM often saves me time/effort the next day, and if anyone is truly bothered by it they could...not check their emails after 6. I've also put out a few fires and helped a few people putting out their own fires via email...and was much happier doing it by email than by having someone reach me through other methods (calling or texting).

If nothing else, this seems like a clear intrusion of the government into things that don't affect them—if someone wants to read or send email at a given time of day, that should be their prerogative.