The CEO added a sender to a safelist but does not receive an important message...

 The reason why the CEO did not receive an important message expected from a trusted sender after adding them to a safelist is because end-user safelists apply to antispam engines only. End-user safelists are lists of sender addresses or domains that end users can create and manage through their quarantine accounts or email clients. End-user safelists allow end users to accept or exempt messages from certain senders or domains from being identified as spam by the antispam engines. However, end-user safelists do not affect other filtering engines such as antivirus, outbreak filters, or content filters. References = User Guide for AsyncOS 12.0 for Cisco Email Security Appliances - GD (General Deployment) - Safelists and Blocklists [Cisco Secure Email Gateway] - Cisco