MailChimp is a great tool to start out with. As you grow your business, though, the limitations of Mailchimp may become clearer and you'll find yourself wanting more customization. ActiveCampaign seamlessly integrates CRMs, email marketing tools, eCommerce stores, and feedback loop systems into one powerful platform so there's no need for additional software or connecting services together (e.g., for customer support chat). That said, if your needs include advanced automation for campaigns and sales funnels (and an enterprise-level CRM), then you may want to consider ActiveCampaign instead. While it's not free, it's a very reasonable price for what you get and is focused on the future of marketing automation.