Microsoft has updated the creation settings for security groups and Microsoft 365 groups in the Azure AD admin center. The changes impose consistency over administrator creation of these groups and probably won’t affect tenants, but it’s good to check. The change makes us ponder why Microsoft doesn’t improve the GUI for other group controls, like those controlling who can create new Microsoft 365 Groups.
Azure B2B collaboration is used by Microsoft 365 Groups-based apps like Teams, Planner, and Yammer to create new guest accounts. You can update settings in the Azure AD portal to stop new accounts from specific domains or restrict guests to a list of known domains. But before you go ahead and update the settings, it’s a good idea to know where existing guest accounts come from. It’s easy to create a report with PowerShell. The next step might be to remove guests from offending domains.