Context: Our study reexamines , in a comparative way, the impact of the reactivity on the satisfaction of the claiming customer from two channels: the email and the telephone. Method: Based on the foundations of the theory of justice, we analyze which of the two channels generates better responsiveness, better justice and ultimately greater satisfaction of the claimant customers. A logistic equation was constructed from 653 customer responses following the processing of their claim, which integrated the impact of responsiveness on the three levels of justice theory (procedural, distributive and interactional). Results: The results of this study underline a greater reactivity and a better satisfaction within the framework of the email channel compared to the telephone channel. The level of procedural fairness was found to be the most important for customers claiming via this channel Conclusion: This study underlines, on the one hand, the importance of the reactivity of the email channel compared to the telephone in the management of complaints. On the other hand, it shows the impact of a smooth and clear process to satisfy the complaining customer and increase his perceived justice.