We all want to replace email. We all say email is broken. We all say we need something else.

As I previously argued, it's not possible. Email is here to stay. It is here to stay because everyone uses it. It is here to stay because, despite everything else, it is useful. It is here to stay because email is a deliverable. Email will always be with us.

But there is one way we can fix email: stop sending it after hours.

We are living in the iPhone and Android era, but let me tell you, kids, I am old enough to remember the Red Blackberry Blinking Light. Beckoning on the nightstand. Beckoning on the weekends.

+ Email sucks: Here is how five startups are trying to fix it +

The Internet was supposed to free us from the office, by making it easier to telecommute. Instead, it has chained us to the office, because we bring it everywhere with us.

That is the main downside of this otherwise wonderful era of enterprise mobility, with document sharing on the cloud, and corporate social networks and all the rest: we can now work anywhere. And because we can, we do. Even though nobody really planned it.

We all know the story. The one who sets a timer so that emails go out in the middle of the night so that he'll appear as hard working. The boss who is angry at 9 am that you didn't respond to the email he sent at 11 pm yesterday. (Although in most cases he won't be visibly angry; he'll just be passive-aggressively angry and make you regret it later.)

The social pressure to work at all hours is just too strong to resist; we all give in, even though it's really in nobody's interest.

Which is why it's up to companies to ban email outside office hours. It's a nice dream, you might say, but it won't fly. It will destroy productivity. I would like to argue that it won't destroy productivity--instead, it will enhance it.

Let's go over it. If you are reading this, you are almost working in some sort of "knowledge" occupation. If so, you are aware of the enormous impact of well-being on productivity. When people can spend time unhindered with their families on nights and weekends, that actually makes them more productive.

Come on, let's be honest: how many people at your office goof off at the office all day and then do their most productive work between 9 pm and 11 pm once the kids are asleep? Not all of them all of the time, I hope. But anyone who thinks "Not in my company!" is deluding themselves. Banning email off hours actually forces us to work more productively in-hours.

And here's another thing. Surely you know what an enormous cost it is for companies to hire workers, and how enormously beneficial it is for companies to be able to retain workers. That money goes straight to the bottom-line in myriad (albeit unseen) ways. Now imagine if your company has this perk. I'm pretty sure that once your employees get used to it, after a few months, they will dread the thought of going to work for another company that doesn't have this rule--even for a 20% pay raise. And I'm pretty sure that they would tell all their friends, all their classmates who are also skilled workers, who will think about working for your company.

OK, maybe there's a nice idea, you might say, but sometimes it's crunch time; sometimes there's an emergency or a deadline and you just need to work around the clock.

That's true. Far be it for me to suggest people shouldn't work hard if they don't have to. Then, easy: have everyone stay at work late. If it's really crunch-time, they'll understand. That way, no need for email. And that way, everyone will be incented to only have crunch-time when it's really crunch-time.

Trust me. Do it. You won't regret it.