This application discloses a method implemented at a server to control information items shared on an instant messaging platform. The server monitors information sharing activities by a public account of the instant messaging platform. The public account is supported by a third party application authorized by the instant messaging platform and has connection with a plurality of individual user accounts of the instant messaging platform. When the amount of information shared by the public account exceeds a predefined threshold, the server partitions the shared information into multiple categories and measures user activities from the plurality of individual user accounts on the categorized shared information. The server selects a policy of restricting the public account from sharing information with the plurality of individual user accounts based on the measurement result, and applies the policy to the public account.