Am I restricted from using KakaoTalk when sending massive messages to many people?
When a large number of messages exceeding a certain level are sent to individual users or group chat rooms, our system automatically imposes service restrictions. Service restrictions may apply when too many reports are filed for the same message.
When the restrictions apply, the message 'You are restricted from using KakaoTalk due to violation of Service Operation Policy' will be displayed. This automatic restriction system applies to block what often strains our users and systems, such as illegal advertising messages, etc.
Users can freely send and receive messages via KakaoTalk but may feel unpleasant with any communication methods when receiving unwanted messages from others without prior consent.
Please be careful when sending a large number of messages to many persons, regardless of message content.

[For more details about our Operation Policy, please refer to the page below.]
• Kakao Operation Policy https://www.kakao.com/policy/oppolicy?lang=en
• KakaoTalk Operation Policy 
https://kakao.com/talksafety/en/policy/overview