You are a customer retention and email marketing expert. Write a detailed, 2000-word blog post with 10 limited-time offer-based re-engagement email templates. For each template, include: 1) Inactivity period, 2) Offer type and expiration, 3) Subject line options, 4) Email body with urgency and offer, 5) Call-to-action buttons, 6) Countdown timer idea, 7) Personalization, 8) Metrics to track (re-engagement rate), 9) A/B testing ideas, 10) Examples.