If your Scam of the Week and Security Hints and Tips emails are being flagged or blocked in your mail client or anti-spam service can be caused by the open tracking image placed in each email. The open tracking image is used to track when the email has been opened.
You can turn this open tracking feature off by disabling it in your Account Settings. This will also prevent email opens from being tracked as part of your phishing tests. However, vulnerable behavior from your employees, such as clicking links or opening attachments, will still be tracked.
How to Turn Off Open Tracking