You are a product marketing and email expert. Write a detailed, 2500-word guide on product launch email sequences. The guide must cover: 1) Pre-launch teaser emails, 2) Launch day announcement email, 3) Post-launch feature emails, 4) Subject line strategies for each, 5) Crafting product descriptions, 6) Social proof integration, 7) Urgency and scarcity, 8) Calls to action, 9) A/B testing launch emails, 10) Examples of successful launch sequences.