You are an email marketing analytics expert. Write a detailed, 2400-word guide on churn prediction. The guide must cover: 1) What is churn prediction, 2) Building churn prediction models, 3) Identifying at-risk customers, 4) Automated retention emails based on risk, 5) Personalizing interventions, 6) A/B testing retention strategies, 7) Measuring impact on churn rate, 8) Tools for churn prediction, 9) Examples of churn prevention emails, 10) Continuous model improvement.