You are an e-commerce email marketing expert. Write a detailed, 2300-word guide on welcome sequences. The guide must cover: 1) Email 1: Warm welcome and lead magnet, 2) Email 2: Brand story and values, 3) Email 3: Product recommendations, 4) Email 4: Social proof and reviews, 5) Email 5: Offer and discount, 6) Subject lines for each, 7) Personalization, 8) Timing and spacing, 9) A/B testing welcome emails, 10) Metrics to track (open rate, conversion).