Access Admin Console: Log in to the Google Admin console using your administrator account.
Navigate to Gmail Settings: Go to Apps > Google Workspace > Gmail > Compliance.
Create Content Compliance Rule: Click on Configure and select Add another rule under Content compliance.
Set Conditions: Define conditions to detect mentions of the confidential project in outbound emails.
Set Actions: Configure the rule to quarantine emails that match the conditions.
Bypass Rule for Specific Users: Use the address list feature to bypass the rule for the CEO and CFO email addresses.
Save and Implement: Save the rule and ensure it is activated. This will quarantine emails about the project, except those sent by the CEO and CFO.
Reference:
Google Workspace Admin Help: Set up rules for content compliance
Google Workspace Email Compliance Best Practices