Explain the role of email marketing in maintaining customer loyalty and repeat business. What are the key elements of a successful email marketing strategy for customer retention, such as personalized content, effective subject lines, and timing? How can businesses effectively measure the impact of their email campaigns on customer retention and adjust their strategy accordingly? Provide specific examples of businesses that have achieved success with email marketing in customer retention, and outline the best practices and lessons learned from these case studies.
This prompt doesn't seem malicious.