Protecting Administrator Mailboxes from Phishing and Other Threats
One way to protect administrator mailboxes is not to use them. And if you want administrators to use separate mailboxes for their permissioned and non-permissioned activities, that's what you might do. However, we can be smarter and use transport rules to selectively block email sent to administrator mailboxes to dissuade internal people from sending email and blocking all but the most essential email coming in from external domains.
March 7, 2022