Act as a seasoned email marketing strategist with 5+ years of experience in e-commerce. Your task is to outline a step-by-step guide for creating a compelling back-in-stock email campaign that drives conversions. Cover the following: [1] How to segment your audience for maximum relevance (e.g., past buyers, wishlist users), [2] Key elements of a high-performing email (subject line, visuals, urgency tactics), and [3] Best practices for timing and follow-up sequences. Include examples of [SUCCESSFUL BACK-IN-STOCK SUBJECT LINES] and [CALL-TO-ACTION PHRASES] that boost click-through rates. Also, address how to leverage [SOCIAL PROOF] (e.g., customer reviews) to build trust. Provide actionable tips tailored for [PRODUCT CATEGORY] businesses.