This study aims to investigate how companies and customers use Twitter to build interactions of sociability. Using a communication-interactional approach and social pragmatics studies, the study analyzes messages posted on the Twitter profiles maintained by two different companies. The focus deals with the topics of the messages and the politeness strategies used to sustain or jeopardize the social space. The results indicate that companies use microblogging to strengthen their brands. The topics and politeness strategies are chosen by the companies with the goal of strengthening their relationships with customers. In addition, we observe that customers use strategies of association that meet the conditions of a pleasant social space. Conversely, customers occasionally use decoupling strategies that exploit the public nature of Twitter to perform actions considered to be less polite or more appropriate to other customer service systems.