Easy Digital Downloads GetResponse:
The Easy Digital Downloads GetResponse extension integrates your Easy Digital Downloads store with GetResponse. The extension automatically subscribes customers to specific lists based on what they purchased. It also allows your customers to opt themselves into a list during checkout. You can also subscribe to customers to specific groups within a GetResponse list.
You can enable a global newsletter list, which all customers can have the option of signing up for during checkout. Also, you will be able to select one or more lists that customers will be automatically subscribed to when purchasing specific products.