Anyone can be kind on a good day. Watch what you type when you’re furious.

Kindness under no pressure is a preference. Kindness under pressure is a character, which is why the furious version of you is the accurate test: it writes faster, reaches further and finds the phrasing designed to land hardest. Nobody is really judged on their calm afternoons. The record that forms around you gets built out of the other ones.

Write the angry message and leave it unsent. Wait an hour, then decide what you actually want to communicate. Very little is lost in the delay, and the sentence you would have regretted never goes out.