Book excerpt: This study aims to study the influence of social networks in post-purchase, that is, in the mentions of customers presented on the internet. Concepts of digital marketing and post-purchase behavior are discussed in this work. Digital marketing means doing marketing through digital tools. It is the set of strategic actions applied in digital media (internet and mobile technologies), to win and retain customers, increasing the company's market share. The main discussion in post-purchase behavior is assessing the cognitive adequacy of the solution chosen in the purchase of a product/service concerning an initial problem, especially when the consumer believes has been deceived. The research problem was: how can post-consumer behavior influence marketing strategies on social media? The Scup tool used as a data collection procedure for surveying social media mentions about AliExpress. As a result, after applying the filter described in the procedures, we obtained 71 records (N = 71) collected in the period from October 29, 2015, to November 4, 2015, which reflect the behavior of the consumer about the post-purchase process. The result of the popularization of social networks has changed the relationship between companies and their publics. In the past those relations was processed through official customer service channels, today is via social networks, where customers expose their positive or negative opinions about product or service purchased by a particular company. Retailers like AliExpress need to improve customer experience throw social media.