Microsoft is pushing out more Microsoft 365 security settings that will increase security by default. You need to assess some of these settings for their impact on your business processes.
One of the new Microsoft 365 defaults has to do with email forwarding. As of September 1, Microsoft has changed the defaults on Microsoft 365 ATP external email forwarding controls. Messages that are automatically forwarded outside the organization will be blocked and a non-delivery report (NDR) will be sent to the user.