In regard to the significant role of information and communication technology (ICT) in educational systems, it becomes increasingly important to gain a better understanding of the features of the language used by learners in the new contexts created by this medium. This paper aims at analyzing politeness strategies including negative politeness, positive politeness, bald on-record, and bald-off record strategies in posts written by Iranian EFL learners in a class blog as an opportunity for asynchronous interaction in response to their teachers and peers. The participants of the study were 14 Iranian EFL learners selected based on their level of language proficiency. There were 1520 politeness utterances across all posts including 800 politeness utterances used when learners were interacting with their instructor and 720 politeness utterances used when learners were interacting with their peers. The collected data were analyzed using content analysis as well as Computer-Mediated Discourse Analysis (CMDA). The results revealed that learners frequently used positive strategies as signs of psychologically close relationship, reciprocity and friendship in a group.