Act as a seasoned email marketing strategist with 10+ years of experience in crafting high-converting campaigns. Your task is to outline a step-by-step process for creating a successful testimonial email campaign that drives engagement and conversions. Focus on [TARGET AUDIENCE], [PRODUCT/SERVICE], and [CALL-TO-ACTION]. Include details on how to select compelling testimonials, structure the email for maximum impact, and personalize content for different segments. Also, provide tips on [TIMING/FREQUENCY] and [METRICS TO TRACK] to measure success. Ensure the tone is [FRIENDLY/PROFESSIONAL/URGENT] and aligns with the brand’s voice. End with a checklist of best practices to avoid common pitfalls.