This won't earth-shattering news that you've never heard before. My advice is to sleep on it.
I have loved e-mail since as long as it's been around. The beauty of it is that there is a documented thread of a conversation. It's great for business; I once worked at a place where a key component of what we did was implementing an online tracking system for work orders. It was marvelous. We had a complete record of a project from ideation to completion. We were able to log specs and changes as a project evolved, offering documented feedback between customer and producer. It allowed us to easily keep track of deadlines, assure quality, and when all was said and done we also had a superb way of measuring our results. Absolutely perfect.
That was a highly evolved "e-mail" ordering system. But most e-mail in a business use is less structured and less formal.
It can also be very deadly. Because of its theoretical permanence, what you write can and may be used against you. e-mail lacks nuance. Something written in a humorous vein can come out sarcastic or flip.
I learned this the hard way.
At one time I was a master of the hot e-mail. And not hot like you'd find on the seamy side of the Internet... hot as in, someone's gonna get burned. Sometimes that was me. Hello, Laymon.
In my ongoing evolution toward complete honesty, along the way I've lost some of the filtration system that can be useful. This is known as "sugar-coating." Sometimes I'd get a bee in my bonnet and knee-jerk a response.
Don't do this.
The problem isn't that you may be right, perfectly right. The problem is in the delivery. Especially if a lot of recipients are privy to the conversation, a hot e-mail can not just put someone on the defensive, it can downright embarrass them. This does not usually foster and develop a collaborative work environment.
This policy also applies to non-work e-mail.
What I learned in that long-ago situation was that if a hot e-mail wasn't time-sensitive, give it a night to see how you feel tomorrow before hitting the "send" button. Maybe you are being too harsh. Maybe you're even wrong. In any event, re-reading your post before sending can allow you to soften the message if need be.
I wrote four hot pages Saturday, and wasn't done when I got interrupted and pulled away from it. Today, Tuesday, it remains exactly where I left it. A lot of what I wrote represents my version of complete truth. But truth wielded like a hammer can be very destructive.
So I haven't sent it, and probably won't send it. It's going into the archive and may one day resurface as a window into a rough day and an unpleasant scene.
But today, I feel mature and wiser. Not a bad approach.