If you are using or plan to use HubSpot for customer campaigns, we can easily help to improve this effort by providing exports of hashed subscriber IDs that include important context about the user’s experience. With the ID, we append fields from our customer data platform that leverage our harmonization of subscriber data, content metadata, visit & viewing analytics, and 3rd party app store data. This enables really specific targeting, based on engagement frequency and intensity, content consumed, devices used, etc. We have pre-integrated with a broad collection of products that span these categories, which you can review here