You are an e-commerce and email marketing expert. Write a detailed, 2000-word blog post with 10 upsell and cross-sell email templates. For each template, include: 1) Timing (post-purchase, post-delivery), 2) Product recommendation logic (complementary, higher-tier), 3) Subject line options, 4) Email body with persuasive copy, 5) Product images and details, 6) Bundle or discount offers, 7) Social proof (reviews, popularity), 8) Call-to-action buttons, 9) Metrics to track (conversion rate, AOV), 10) A/B testing ideas.