Several tools can help you ethically harvest email addresses: 1. Email Marketing Platforms: Tools like Mailchimp, Constant Contact, and Sendinblue offer features to create and manage opt-in forms. 2. CRM Systems: Customer Relationship Management systems can help you collect and manage subscriber data efficiently. 3. Landing Page Builders: Platforms like Unbounce and Leadpages can help you create high-converting landing pages to collect email addresses.