From a user perspective, unsolicited bulk Zalo messages are deeply intrusive. Unlike email (with separate spam folders), Zalo pushes notifications for every message. Recipients feel violated when a stranger or business invades their private chat list.
Zalo, Vietnam’s most pervasive over-the-top (OTT) messaging platform, has evolved from a simple communication tool into a critical ecosystem for business-customer interaction. The concept of "Zalo Bulk" refers to the practice of sending high-volume messages—text, images, files, or interactive cards—to numerous recipients simultaneously. While official Zalo Business and Zalo Official Account (OA) platforms provide compliant bulk APIs, a parallel gray market of unauthorized bulk-sending tools has emerged. This paper examines the technical architecture of Zalo’s messaging system, distinguishes legitimate bulk methods from prohibited ones, analyzes marketing efficacy, and discusses legal and ethical implications under Vietnam’s Cybersecurity Law and Data Protection frameworks. Finally, it proposes best practices for sustainable bulk messaging. zalo bulk