This paper reports on an ongoing project in the area of intentional impoliteness as perceived by the participants and as marked in discourse in the asynchronous Computer Mediated Communication (CMC) context. We focus on occurrences of "impolite talk" and examine the context bound nature of communicative strategies adopted by the interactants in order to deliberately do impoliteness. We also analyze how impoliteness is lexicalized in relation to the inherent characteristics of the CMC context. Specifically, this paper draws on a sample of data from two Communities of Practice (CofP): Greek students and professional academics. 200 posts were collected from interactions where dispute occurred. Special attention is paid to the use of spelling and punctuation and one interactional discourse particle, namely re (untranslatable), in unmitigated confrontational disagreement that breaches the norms of unmarked behaviour in the two CofPs. Our preliminary findings show that (im)politeness is firmly embedded in the micro (discourse) and macro (social) context. The impoliteness strategies employed by the interactants indicate different judgements of what constitutes marked behaviour and are contingent on factors such as the overall purpose of communication, the co-constructed norms of the forum, the relationship between participants and the dynamic group identities which the interactants call upon in any given situation. © 2010 Walter de Gruyter GmbH & Co. KG.