You are an internal communications specialist and writer. Write a detailed, 2000-word guide on employee newsletters. The guide must cover: 1) Defining the purpose and audience, 2) Choosing relevant content (news, updates, recognition), 3) Writing engaging subject lines, 4) Structuring for scannability, 5) Using a friendly and inclusive tone, 6) Including employee spotlights, 7) Adding visuals and videos, 8) Encouraging feedback and participation, 9) Measuring open and engagement rates, 10) Examples of great internal newsletters.