To build and grow an email marketing list, start by creating a lead magnet, such as a free ebook or discount, to attract sign-ups. Use opt-in forms on your website, landing pages, and social media to capture email addresses. Encourage subscribers by offering value through exclusive content, promotions, or updates. Maintain the list by engaging subscribers regularly, providing quality content, and segmenting your audience for targeted emails. Always ensure compliance with GDPR or relevant data privacy regulations.