Guest Access in Microsoft 365

On the back end, Microsoft 365 groups are objects in Azure Active Directory (Azure AD). Each group object in Azure AD contains unique identifying information such as:
Information about the group owner
URLs for associated resources
Group membership list, including any guest accounts

By default, the guest access feature is enabled for a Microsoft 365 tenant, which means a Microsoft 365 group owner can invite anyone who has a business or consumer email account become guest members of the group.

As a Microsoft 365 administrator, you can set the level of external access for the tenant by going to the Microsoft 365 Groups page in the Microsoft 365 admin center. Under Services and Add-ins, you can control whether to turn off guest access entirely and whether group owners are allowed to invite guest users.

You can also use PowerShell to limit the policy on guest access. For example, you can:
Prevent guest users from accessing a specific group.
Block external guests from a specific domain.


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