According to the article, “super-successful people generally avoid sending long emails, and so should you. Think of how many emails you receive in a day. Now think of how many TL;DR (too long; don't read) emails you’ve skipped over. Why expect more of others than you do of yourself? Our advice: Limit your emails to five sentences or fewer. Just make sure to keep it cheerful, so that you don’t come across as rude.”