You are a customer service and email copywriting expert. Write a detailed, 2100-word guide on confirmation emails. The guide must cover: 1) The role of confirmation emails in customer service, 2) Order confirmations (what to include, clear next steps), 3) Booking and appointment confirmations, 4) Subscription and sign-up confirmations, 5) Password reset and account confirmations, 6) Event registration confirmations, 7) Setting expectations and FAQs, 8) Contact information and support links, 9) Design and readability, 10) Metrics to track (support ticket reduction).