M365 Changelog: (Updated) Microsoft Teams: Block a user for your organization – Sep 13, 2024

MC888879 – Updated September 13, 2024: Microsoft has updated the rollout timeline below. Thank you for your patience.

The availability of the delete API (removeallaccessforuser API) does not stop a malicious user from resending a Microsoft Teams message to the same victim. To help prevent that, a block user feature will allow the admin to block the malicious user from reaching out again. To make this possible, Microsoft will use a similar feature as the allow/block list in federation identity credentials to block the malicious user from the entire organization.   

This message is associated with Microsoft 365 Roadmap ID 411138.

When this will happen:

General Availability (Worldwide): Microsoft will begin rolling out early November 2024 (previously late October) and expects to complete by mid-November 2024 (previously early November).

How this will affect your organization:

Admins can now set up a list of users that are blocked from collaborating with their organization. If a user is added to the block list, your organization will not be able to have 1:1 and group chats with these users. If chats already exist before a user is added to the block list, the blocked user will be removed from the chat.

This feature is turned off by default. 

What you need to do to prepare:

If you wish to use this feature, navigate to external access organization settings to turn this feature on and add users to the block list.