There is no way to satisfy "Block Exchange Forwarding" in ISPM while a single forwarded mail address exists in the organization. There are common and unavoidable business use cases for forwards though. For example, we have a support mail box (help@ourdomain.com) that forwards to an outside JIRA mailbox for ticketing. We should be able to enable the prevent-forwarding ISPM control in a way that allows this business process to continue to function.

Ideally, there would be an admin-approved exception mechanism for allowing specific mailboxes to be forwarded, while preserving and enforcing the "block accounts from setting up forwarding" behavior.