You can’t begin to personalize your campaigns if all you have is an email address, so work to figure out what data you already have. Do you have information on past purchase behavior, length of time on your email list, customer status, or geography? All of these areas can be leveraged for personalization, which will, in turn, improve list quality. Where does this information live? Is it in your CRM, e-commerce platform, or somewhere else? Integrations can help you combine your email list with outside information.