Bulk | Zalo

User visits website → Clicks "Receive Zalo deals" → Redirects to Zalo OA → Clicks "Follow" → OA sends confirmation message: "You are now subscribed. Reply YES to confirm." → User replies YES → Record stored. End of paper.

Abstract 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. 1. Introduction As of 2025, Zalo boasts over 75 million active users, penetrating more than 75% of Vietnam’s internet-connected population. Unlike global giants like WhatsApp or Telegram, Zalo is deeply integrated with local habits: phone-number based registration, minimal data usage, and features tailored to Vietnamese culture (e.g., ZaloPay, official government accounts). For businesses, reaching customers on Zalo is not optional—it is essential. zalo bulk

| Metric | Legitimate OA | Gray-market tool | |--------|---------------|------------------| | Delivery rate | 98.7% | 52.3% (due to blocks) | | Open rate | 41% | 11% | | Click-through rate (CTR) | 8.2% | 1.4% | | Spam report rate | 0.3% | 18% | | Account ban rate (sender) | 0% | 94% within 1 week | User visits website → Clicks "Receive Zalo deals"

"Bulk messaging" refers to sending identical or personalized messages to a large audience (hundreds to hundreds of thousands). The demand spans e-commerce flash sales, banking notifications, educational institution announcements, and political campaigns. However, Zalo’s terms of service strictly regulate bulk behavior to prevent spam, fraud, and network abuse. This paper examines the technical architecture of Zalo’s

Case example: In 2024, a Vietnamese fashion retailer used ZaloBulkPro to send 80,000 promotional messages. Within 48 hours, all 25 employee Zalo accounts were permanently banned, and the company’s domain was blacklisted by Zalo. Sales dropped 40% over next quarter. 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.