On your Email Campaigns Dashboard, you have access to several reporting metrics essential to analyzing the performance of each of your email campaigns. You'll notice that for your sent campaigns, Opens & Clicks are clickable links:
From here, click Email opens. Since they engaged with your campaign, it's likely they are displaying a higher intent to buy. You can reach out to them to offer a VIP incentive for being an active subscriber, or just send them more information on the promotion you're having! Don't forget to change your Subject Line and Pre-header text!