Your first draft of an email can be angry. The one you send can’t.

Writing something and sending it are two separate acts, and keeping them separate is the whole trick. The angry draft is useful, because it moves the feeling out of your chest and onto a page where you can look at it. Sending it hands that feeling to somebody who will keep it far longer than you will. The gap between the two is where your judgement lives.

Write the draft and then do not send it tonight. Save it, sleep, read it again in the morning. Send the version that says what you want to happen next.