This document provides guidelines for writing polite emails, including: 1) When emailing someone you don't know, include a clear subject line and greeting, keep paragraphs short and direct, and avoid jokes or informal language. 2) When continuing an email conversation, it's okay to leave out greetings in follow-up emails, respond in a reasonable time frame, and trim old messages from replies. 3) Sensitive information like passwords or large attachments should generally be avoided, especially when initially contacting someone.