To remember the value of keeping emotions in check when crafting a business message, a writer should need nothing more than to live up to the Chinese proverb, "The palest ink is better than the best memory."
No matter how upset you are, anger does not belong in business writing. After you cool off, your angry document lives on. Let your high emotions motivate you to write the first draft--but then sit on your hands and don't press the send button. Weed out the pointless anger or disappointment in favor of purposefull, direct language. Move the business forward!