Fostering Responsibility in Email Marketing: A Contextual Restless Bandit Framework

Abstract

Email marketing is increasingly criticized due to ethical concerns, as bulk email campaigns often result in spam, reduced engagement, and negative user experiences. In addition, there is increasing awareness of the environmental impact, as these large-scale campaigns contribute to carbon emissions. To address these issues, we introduce QWIC-Fair (Q-learning Whittle Index with Context and Fairness), an algorithm that operates within a Contextual Restless Multi-Armed Bandit framework. QWIC-Fair leverages implicit feedback to learn the dynamics of user interactions and thus target users with relevant content. In this model, each user represents an arm of the bandit, evolving as a Markov Decision Process that captures state transitions reflecting their interactions with email contents, while accounting for contextual information. The algorithm also incorporates a fairness constraint to ensure balanced selection and to avoid repetitive targeting of the same users. The experiments conducted, using synthetic and real-world data, show that QWIC-Fair  outperforms existing email marketing approaches.