insom and lil have already said what I would but better. I'll just add - my friend and I have an email writing team. Whenever we need to call someone an asshole, ask someone a favor, ect, we work on drafts and proofread for each other. Having a buddy to proofread and check for tone is huge. If you have a friend you can enlist you can send out your stuff for review at 2:00am you can have a reply by the next afternoon when your brain is more awake and send it then.
This. Don't write emails angry (unless you are doing it solely for therapeutic purposes and will be immediately deleting it) and try to have at least one person look over important or emotional emails. My coworker and I did this for each other constantly. Then we were both emotionally invested in a shit storm and had no clue what to do. We had gotten so good at not writing an email angry / without being rewritten more objectively that we pretty much forced ourselves to ignore it for a full day and approach fresh the next day. We also had to stealthily avoid in-person contact with the other two guys in the office as well. I never realized how fucked and silly offices and jobs in general are.Whenever we need to call someone an asshole, ask someone a favor, ect, we work on drafts and proofread for each other.
We have project managers whose job is mostly to be a filter. They take emails from clients, bounce them back until they make some kind of sense, pass them along with color commentary and pictures of cats, and then rephrase our replies with less nerdrage and mockery. They are the only people with "manager" in their job title I like. It'd take me all day to figure out how to word some things gently before we got them. Now I can say what comes to mind when people email thousands of names and social security numbers in the clear, and not waste most of a day trying to figure out how to say "don't do the stupid and irresponsible thing" without using synonyms of "stupid" or "irresponsible."