What is the most effective method for preventing users from accidentally sharing sensitive data externally through Microsoft Teams chat?

The most effective method for preventing users from accidentally sharing sensitive data externally through Microsoft Teams chat involves a combination of Data Loss Prevention (DLP) policies and Microsoft Information Protection (MIP) sensitivity labels, along with user training and awareness. First, implement DLP policies specifically targeted at Teams chats and channel messages. These policies should be configured to detect sensitive information types, such as credit card numbers, social security numbers, or other confidential data, within chat messages. Configure the DLP policy to take action when sensitive information is detected, such as blocking the message from being sent externally, alerting the sender and/or administrators, or prompting the user to confirm that they intend to share the information externally. Next, utilize MIP sensitivity labels to classify and protect sensitive documents before they are shared in Teams chats. Apply sensitivity labels that restrict external sharing to documents containing confidential information. When a user attempts to share a document with such a label in a Teams chat, the sharing restrictions defined by the label will prevent external users from accessing the document. Implement user training programs to educate users about the risks of sharing sensitive data externally and how to identify and handle sensitive information appropriately. Ensure users understand the organization's policies regarding data sharing and the tools available to protect sensitive information. Finally, regularly monitor DLP policy violations and user activity to identify potential security risks and areas for improvement. This proactive approach helps prevent accidental data leakage and ensures that sensitive information remains protected within the organization's control.