LPT: When you're angry at someone, write the message you want to send but save it as a draft and wait 90 minutes before deciding whether to send it.
I've been doing this for about four years and it has saved me from a significant number of conversations I would have regretted.
The way it works: when I'm upset enough that I want to send a sharp message to someone, I write exactly what I want to say. I don't soften it, I don't edit for tone, I just write the thing. Then I save it as a draft and set a 90 minute timer. That's it. When the timer goes off I read it back and decide whether to send, revise, or delete.
The reason 90 minutes specifically: it's long enough that the acute emotional spike has typically passed but short enough that I haven't just forgotten what I was upset about and let something go that actually needed to be addressed. An hour is too short, in my experience. Two hours starts crossing into "maybe I'll just deal with this tomorrow" territory which sometimes means never.
What I've found over four years is that roughly 60 percent of the time I either delete the message entirely or rewrite it from scratch in a much more productive way. About 30 percent of the time I send a lightly edited version. Maybe 10 percent of the time I actually send something close to what I originally wrote, and in those cases I usually feel okay about it because I've confirmed the anger was proportionate after thinking it over.
The thing this protects you from is not just obvious blowups. It protects you from the subtly cutting message that seems reasonable in the moment but lands badly, the passive aggressive sign-off, the email to a coworker that technically says nothing wrong but sets a tone you can't walk back. Those are the ones that do the most quiet damage in professional and personal relationships and they're the ones most likely to feel justified when you're in the middle of writing them.
Write it. Set a timer. Read it back with slightly different eyes. The message will still be there if it needs to be sent.