An instant messaging system for securing chat sessions containing confidential subject matter during instant messaging from external entities, the system comprising: a rules engine module configured to continuously build and update a set of rules used to determine when a chat session between a first chat party and a second chat party during an instant messaging session contains confidential or uniquely classified subject matter by loading at least one default rules or previous session rules and enabling a user to provide user-defined rules until the instant message session is ended; and an instant messaging module configured to secure the contents in the chat session based on pre-defined user settings, the contents in the chat session being secured when the contents in the chat session is determined to contain confidential subject matter derived from the set of rules, the chat session is further secured by limiting the exposure of the contents in the chat session to third parties when the chat session is determined to contain confidential subject matter while enabling the first chat party and the second chat party to view the contents in the chat session.