Teams Chat and Meetings Whitelisting

Hi @Raymond Brooks

Welcome to Q&A Community! 

Thank you for reaching out with your question regarding chat and meeting configurations in Microsoft Teams. 

It is possible to configure Teams so that specific users can chat only with internal and whitelisted external domains, while still allowing them to host or join meetings with internal and external participants without domain whitelisting. However, there are some certain steps that you need to set up as listed below. 

Step 1: Confirm Organization-Level External Access 

1. Sign in to the Teams Admin Center. 
2. Navigate to Users > External Access. 
3. Ensure that External Access is enabled for your organization. This is required for any federation or external chat. 

For reference: Learn more about managing external access  

Step 2: Create a Custom External Access Policy 

Microsoft recently introduced custom External Access policies that can be assigned to users or groups. These policies allow you to: 

• Use organization settings 
• Allow all external domains 
• Allow only specific external domains (whitelist) 
• Block only specific external domains 
• Block all external domains 

However, the feature is fully functional via PowerShell today. As the feature is being rolled out this September, changes made through PowerShell are effective but will not appear in the Teams Admin Center UI until the feature reaches full General Availability (expected mid-December 2025). 

Once GA is complete, the UI will support these configurations for easier management. Please check the Roadmap for more details. 

Here are the steps to create a customer external access policy using PowerShell: 

1. Open PowerShell and connect to Microsoft Teams using Connect-MicrosoftTeams  
2. Create a new External Access policy with New-CsExternalAccessPolicy  
3. Enable CustomizeFederation at the tenant level with Set-CsTenantFederationConfiguration -CustomizeFederation $true  
4. Assign the policy to specific users using Grant-CsExternalAccessPolicy  
5. Repeat for additional users. 

For detailed information, please refer to these articles:  

• Connect-MicrosoftTeams (MicrosoftTeams) | Microsoft Learn 
• New-CsExternalAccessPolicy  
• Grant-CsExternalAccessPolicy

 Step 3: Configure Meeting Settings for External Participants 

1. In Teams Admin Center, go to Meetings > Meeting Settings. 
2. Enable Anonymous Join if you want anyone with the link to join. 
3. Review Meeting Join and Lobby under Meeting Policies:  
   • Decide who can bypass the lobby (e.g., everyone in your organization). 
     • External participants will wait in the lobby unless allowed by meeting options. 
4. Ensure Guest Access is enabled if you plan to invite external users as guests. 

For reference: 

• Learn more about planning meetings with external participants   
• Manage anonymous participant access  

After completing the configuration, test with a user who has been assigned the custom policy to confirm functionality. Make any necessary adjustments to ensure compliance with your organization’s governance requirements. 

Please note that these changes can take up to 24 hours to fully propagate, so allow sufficient time for the settings to apply before testing. 

Feel free to correct me if there are any misunderstandings or if you need further assistance. I am happy to assist you further.

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