Presents the initial findings of a genre-based case study at a large Swedish company, with a record of early use of internal e-mail (1982). The design of the particular e-mail system was closely mapped to the organizational hierarchy. One of our informants kept one week of incoming e-mail messages. We then asked questions about each message and how it related to the work of the informant and to the organization. Based on the messages and the interviews, we clustered the messages into different genres. Most of the literature on genres of organizational communication has focused on the genres themselves, e.g. e-mail messages constituting different instances of genres. We found, however, that many messages, rather than being instances of genres, were part of informal conversations. In these conversations, however, it was common to discuss and negotiate which genres were appropriate to use in different situations. © 1999 IEEE