DoppelBrand: Executive impersonation with Reply-To mismatch and financial lure

This rule detects potential Business Email Compromise (BEC) attempts where an attacker impersonates an executive (CEO, CFO, etc.) via email. It identifies emails where the Sender's display name suggests a high-level executive role, but the domain of the Reply-To address differs from the sender domain, which is a common indicator of a fraudulent routing attempt. The rule further narrows this down to emails with subject lines typical of financial-themed urgency or requests.