Automatic e-mail forwarding should be inventoried and blocked as far as possible. This article from Microsoft explains the principle and outlines the short-term developments.

Default forwarding is already a thing of the past. It will no longer be the norm, but the exception. The new rules will have an impact on organizations that have been using it without much thought.

Typical use case: injecting incoming e-mails into a third-party application, such as a CRM.