LPT: When you're about to send an angry email, write it, then move it to drafts and come back in 20 minutes. You'll almost always rewrite it.
This sounds obvious but I genuinely didn't do it consistently until about two years ago and it's changed how I handle conflict at work more than almost anything else.
The thing is, the 20 minutes isn't really about cooling down. It's about the shift that happens when you reread something you wrote while activated. When you're in the moment, the email feels measured and justified. You've laid out your points, you've been clear, maybe you've been a little sharp but they deserve it. Then you come back and read it as if someone else wrote it and suddenly you can see exactly how it lands. The sarcastic line that felt satisfying to write reads as petty. The part where you cc'd their manager feels like escalation you'll have to live with. The tone that felt firm feels hostile.
I work in a job with a lot of stakeholder communication and I have a folder of emails I never sent that I occasionally look through. Some of them are things I'm genuinely glad I didn't send. A few of them I eventually did send, but in a much more precise and less emotionally loaded form. One of them I look at sometimes and I'm not sure what I was thinking, it reads like a resignation letter written by someone having a bad week.
The other thing this does is occasionally clarify that you're actually right to be frustrated and the email just needs tightening, not softening. That happens too. But you can only tell the difference from the outside.
The drafts folder is doing a lot of work in my professional life. I'd recommend it to basically anyone who communicates with people they find difficult.