The quickest way to build a niche email list is by offering value to your audience. You can create a free resource like an eBook or guide specific to your niche. You can use targeted ads to drive traffic to your sign-up form. You can add pop-ups to your website to capture emails quickly. You can promote your list through social media platforms. You can host a webinar and ask attendees to sign up. You must focus on attracting engaged and interested subscribers. You should ensure your list grows organically and complies with privacy laws for the best results.