Teams External Access Settings Not Applying: CommunicationWithExternalOrgs and CustomizeFederation Issues

Diermeier Lamaralus 180 Reputation points
2025-09-16T07:18:36.02+00:00

I'm working on configuring External Access policies in Microsoft Teams to allow only specific users within our organization to communicate with external domains.

However, I'm hitting a roadblock when attempting to update the CommunicationWithExternalOrgs parameter to AllowAllExternalDomains. I receive the following error:

Access denied. The field CommunicationWithExternalOrgs is not allowed to be set.

In an attempt to work around this, I also tried enabling -CustomizeFederation at the tenant level by setting it to $true. While the command completes without any error, the setting remains unset -CustomizeFederation stays blank and doesn't seem to take effect.

Microsoft Teams | Microsoft Teams for business | Other
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Answer accepted by question author
Anonymous
2025-09-16T09:16:48.2766667+00:00

Hi @Diermeier Lamaralus, 

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

Firstly, please note that these settings must be configured by a Teams Admin or Global Admin. Kindly ensure that you have the necessary permissions to make these changes. 

Based on my research and the official Teams PowerShell Release Notes, the CustomizeFederation parameter has been deprecated from the Get-CsTenantFederationConfiguration and Set-CsTenantFederationConfiguration cmdlets. This is why the setting cannot be updated and remains blank. 

You can find more details here: Microsoft Teams PowerShell Release Notes - Microsoft Teams | Microsoft Learn 

User's image

To configure tenant federation settings, I recommend using: 

Set-CsTenantFederationConfiguration -AllowFederatedUsers $true 

Or 

Set-CsTenantFederationConfiguration -AllowedDomains "domain.com" 

depending on your specific needs. 

For your reference: Set-CsTenantFederationConfiguration (MicrosoftTeams) | Microsoft Learn 

To create a policy that allows all external domains, you can use:  

New-CsExternalAccessPolicy -Identity "AllowAllExternalPolicy" ` 
    -CommunicationWithExternalOrgs "AllowAllExternalDomains" ` 
    -Description "Policy allowing all external domains" 

For your reference: New-CsExternalAccessPolicy (MicrosoftTeams) | Microsoft Learn 

After that, you can proceed to assign the policy to your users. 

Please understand that our initial response may not always resolve the issue immediately. If you get stuck at any step or have any additional questions during the process, feel free to leave a comment under this post. 

 I’ll be happy to assist you further. 

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

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