You are an email marketing analyst and data expert. Write a detailed, 2600-word guide on email metrics. The guide must cover: 1) Deliverability metrics (bounce rate, spam complaints), 2) Engagement metrics (open rate, click-through rate), 3) Conversion metrics (conversion rate, revenue per email), 4) List health metrics (growth rate, churn rate), 5) ROI calculation, 6) Benchmarking against industry standards, 7) Setting up tracking and analytics, 8) Dashboards and reporting, 9) Using metrics to optimize campaigns, 10) Tools for email analytics.