Digital technology is leading the transformation of business models into sustainable ones, expanding and changing the competitiveness scenario. This paper aims to promote a new sustainable retailer model shaped by contingent free shipping theory and the optimisation of the customer’s journey, enriching the scientific literature by proposing a consumer behavioural model that highlights the contribution of four selected touchpoints to the sustainable transformation of SMEs. The research was elaborated by deploying a framework that presents five analysis methods, namely, an additive function construction, a TOPSIS method, a Spearman rank correlation coefficient calculation, a content analysis and an analytic hierarchy process, which engender the new model. Discovering nine distinguished categories of e-tailers, the sustainable retailer profile was developed and the touchpoint with the greatest contribution to the transformation process was identified. The results of the study allowed the authors to propose the model as a solution to withstand the preponderant negative experience provided by analysed e-tailers to digital buyers, representing the opportunity for SMEs’ sustainable transformation and long-term growth in a competitive, ever-growing market.