Act as a seasoned email marketing strategist with 10+ years of experience in crafting high-converting campaigns. Your task is to analyze how different tones (e.g., formal, casual, enthusiastic, empathetic) in email subject lines and body content influence open rates, click-through rates, and overall engagement. Provide actionable insights on optimizing tone for [TARGET AUDIENCE], [INDUSTRY], and [CAMPAIGN GOAL]. Include examples of before-and-after email copy, A/B test results, and psychological triggers that resonate best. Focus on [KEY METRIC] (e.g., conversions, replies) and how subtle linguistic adjustments can improve performance. Back your recommendations with data-driven evidence.