Block creation of (Exchange) forwarding rules

Question

Want to block the possibility for users to create a auto-forwarding rule in exchange.

Answer 1

There are several different methods users can use to forward their messages. For a complete list, as well as the methods to disable them, refer to this article: https://exchangepedia.com/2015/03/disable-automatic-forwarding-of-email-in-office-365-and-exchange-server.html
In addition, Exchange Online Protection now blocks external forward by default: https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/external-email-forwarding?view=o365-worldwide