You can try to find a list of subscribers. However, your emails will probably get flagged as spam or the subscribers will ignore them, (considering that you're an unknown sender). It is also quite possible that your emails will bounce due to unexisting email accounts, or email accounts that have their mailboxes full.
A better way to grow your own subscriber list is to deliver high-quality content, offer your website visitors a chance to get your email newsletter, and invite people following you on social media to subscribe to your newsletter. You can also ask customers to sign up on your thank you page when they make a purchase and get their emails that way, and offer promotions, exclusive offers, or free stuff.