There are many organisations who use HubSpot for Prospecting data, the main points to make sure is that you are clear on the legal basis under which you are uploading that data and communicating with it (Legitimate interest if you have no prior relationship), you have clear unsubscribe links both in your marketing and sales emails and that you are clear in your terms of service how long you will store that data for (a reasonable time frame according to GDPR guidelines) - Keep your prospecting data and active lead data well segmented using lifecycle stage or Lead status rules and try to be as ‘Inbound’ as possible with your communications - be helpful with your content, be respectful with your frequencies