You are a sales and email copywriting expert. Write a detailed, 2300-word guide on cold email copy. The guide must cover: 1) Research and personalization, 2) Crafting compelling subject lines, 3) Opening with a hook, 4) Demonstrating value and relevance, 5) Clear and specific ask, 6) Keeping it concise, 7) Social proof and credibility, 8) Follow-up sequence strategies, 9) A/B testing cold emails, 10) Compliance and best practices.