Microsoft Teams — Disabling Chat with Personal Accounts

Microsoft are enabling a feature which allows Teams chat with external users using personal Microsoft accounts (e.g. Hotmail, Outlook etc). This potentially opens Teams to data loss or spam from external users, therefore many organisations will want to disable this feature.

Note that this setting will default to On unless you explicitly turn it off.

Via Teams Admin

1. Log in to Teams admin.
2. Click Users > External access.
3. Under Teams accounts not managed by an organization, toggle People in my organization can communicate with Teams users whose accounts aren’t managed by an organization to Off.

Via PowerShell

Import-Module MicrosoftTeams
Connect-MicrosoftTeams
Get-CsTenantFederationConfiguration   # Check the current setting
Set-CsTenantFederationConfiguration -AllowTeamsConsumer $false   # Turn it off

And that’s it! Quick and easy, and recommended for all new or existing tenants unless you want Teams to be open to personal accounts.