A revolutionary medium of communication in the 1990s, email has progressively revealed its limitations and even emerged as a source of information overload. In response, many companies have adopted enterprise social networks (ESN) as alternative communication channels, though surprisingly little research attention focuses on the articulation process by which both technologies influence work practices, through complementarity or substitution effects, or addresses the information overload challenge. In this article, we detail an empirical, qualitative study of the articulations of emails, ESN, and other collaborative tools in organizations, on the basis of 1) an exploratory study of three companies from various sectors, 2) an auto-ethnography that relies on participant observations from a large French telecommunication company, and 3) a validation through in-depth discussions with experts. The resulting causal framework of the articulations of usage factors of email, ESN, and specialized collaborative tools at work contains three main contributions. First, we enhance understanding of information overload by clarifying that it is not intrinsic to email and by analyzing the emerging notion of "collaborative overload." Second, we determine that ESN may not be the solution for fostering new behaviors. Third, workplaces do not need ESN tooling but rather require a digital transformation strategy, with more emphasis on meeting employees' needs instead of focusing solely on an ESN's promise for altering workplace culture and practices.