If you're an Etsy seller with a busy shop – say, 500 orders last month – great job! But here's the deal: just because your shop got sales the last month doesn't mean you can contact your past buyers with marketing emails without their consent.

Remember:

- Transactional Emails: Transactional emails are defined as those related to order confirmations, delivery notifications, and other emails directly tied to the customer's purchase.

- Subscriber Emails: These are marketing emails, which are used to promote products, offer discounts, and engage with customers.

As a seller on Etsy, you're allowed to send transactional emails, and it's even recommended by Etsy. However, when it comes to marketing emails (promotional emails), you 
must obtain explicit consent from the buyers before sending them any type content that is not related to their purchase.

So, basically, it is not advisable to add and initiate the sending of marketing emails to these past customers. Etsy prohibits this unless the emails are directly related to their current purchase.

Here more information about how to start building your email list.