Klaviyo is the best in class email marketing solution for eCommerce. It's powerful because it connects to your store, and you can create awesome customer segments based on past purchasing behaviors, customer preferences, and even future predictions of spending.
Stamped.io is a tool to collect customer reviews. It's got nifty features including the ability to capture review feedback directly inside email, or the ability to request reviews via Facebook Messenger. Easily leverage the reviews you've gathered by displaying them on your product pages.
Zendesk Sunshine (formerly Smooch) is a CRM tool focused on conversational commerce. With Sunshine, you can communicate with your customers across any channel quite seamlessly. From SMS, to Telegram, Facebook chat, Whatsapp and Twitter - You can centralize all of your communications in one place.
Gorgias centralizes all your support tickets in one place and enriches them with lots of extra context about a buyer's profile. Through Gorgias, you can connect directly to your eCommerce store and edit orders, modify subscriptions, and refund payments without leaving your helpdesk.