You can generate an email list of a targeted niche by starting with online research. You can find websites that cater to your niche. You can sign up for newsletters to collect emails. You can also use social media to connect with people in your niche. You can join relevant groups or forums and interact with potential leads. You can offer valuable content like eBooks or webinars in exchange for emails. You can use lead generation tools that help you collect emails based on specific interests. You must ensure you comply with privacy laws when collecting and using email data.