The e-commerce market is dynamically growing. Attractive purchase prices, low cost, short delivery time, and convenient delivery places motivate consumers to shop online. In turn, the free return possibility motivates customers to buy more and more products and then return them to the retailer. As a result, courier companies face increasing challenges regarding return logistics in e-commerce. According to Hazen (2011), return logistics focuses on the backward flow of products from customers to suppliers. Rogers and Tibben-Lembke (1999) defined it as “the process of planning, implementing, and controlling the efficient, cost-effective flow of raw materials, inprocess inventory, finished goods and related information from the point of consumption to the point of origin to recapture value or proper disposal”. Most of the research focuses on forward logistics (Stock et al.,2002; Bernon and Cullen, 2007) or last-mile delivery in terms of cities (Burlando & Vella, 2021). There are not many papers which are related to sustainable return logistics (Wenjuan, 2015; Velazquez, Chankov, 2019). This paper aims to identify the preferences of e-customers and the possibility of their change in return logistics to organize it sustainably. To achieve this goal, the conjoint analysis was applied based on a survey conducted among 1,100 e-customers in Poland and 500 e-customers in Brazil. In the research the fuzzy methods will be applied as: fuzzy cognitive maps that is usually used to structuring the research problem and fuzzy taxonomy that allows us to analyse in more deeply sense the preferences of e-customers. The paper results from the research project: Sustainable last-mile delivery and returns on the e-commerce market. Perspective of various stakeholders Funded by the Polish National Science Centre, No. 2018/31/B/HS4/03711@en