Research has conventionally viewed feedback from the point of view of the input, thus analysing only one side of the feedback relationship. More recently, there has been an increased interest in understanding feedback-as-talk. Feedback dialogue has been conceptualised as the dynamic interplay of three dimensions: the cognitive, the social-affective and the structural. We sought to explore the interactional features of each dimension and their intermediary effects on students. We analysed students' feedback dialogue excerpts as cases using interactional analysis. Analysis involved iterative inductive and deductive coding, and interpretation of feedback texts generated in an online course. The cognitive, social-affective and structural dimensions were interwoven within excerpts of feedback dialogue with effects on learners that extended beyond the immediate task (e.g. reframing of learners' ideas, critical evaluation). The interactional features of each dimension include: cognitive (e.g. question asking, expressing oneself); social-affective (e.g. disclosure, expressing empathy); and structural (e.g. longitudinal opportunities for dialogue, invitational opportunities). The study provides evidence that strengthens the call for reconceptualising feedback as a dialogic and relational activity, as well as supporting the view that dialogic feedback can be a key strategy for sustainable assessment.