Is it possible for administrator of an organization to read chats with external users not registered to the organization?

Hello @Ray Carsten

Thank you for posting your question on the Microsoft Q&A forum. 

The direct answer to your question is: Yes, administrators can access chat content between internal users and external users under certain conditions, primarily for compliance and legal purposes. This is possible through tools like Microsoft Purview eDiscovery and Content Search, which allow organizations to search and export Teams chat data stored in Exchange Online mailboxes. 

Any communication sent or received by an employee using their corporate account is considered data belonging to that organization. When your user chats with an external person, a copy of that conversation is stored within your organization's Microsoft 365 environment. This data is subject to your company's data governance and retention policies, just like internal chats and emails are. 

You can refer to the official Microsoft documentation here for more details: 

• Conduct an eDiscovery investigation of content in Microsoft Teams 
• Finding content in Microsoft Teams in eDiscovery 
• Manage external meetings and chat with people and organizations 

I hope this detailed explanation and the official documentation provide the definitive answer you were looking for. If you need help or have any other questions, I’m here to assist you.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". 

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.