Information
This policy setting allows you to determine if Excel files in Outlook attachments open in Protected View. The recommended state for this setting is: Disabled. Enabling this setting allows Outlook attachments to open outside of Protected View. Email is a common way to spread files containing malicious code. This could allow malicious code to become active on user computers or the network.
Solution
To implement the recommended configuration state, set the following Group Policy setting to Disabled. User Configuration\Administrative Templates\Microsoft Excel 2016\Excel Options\Security\Trust Center\Protected View\Turn Off Protected View For Attachments Opened from Outlook Impact: Opening Office files, such as the Office versions of Word, Excel, PowerPoint, and OneNote, is a common action. Users are unlikely to notice much difference when opening and viewing files in Protected View. Users who want to modify these kinds of files must save them to a safe location and then open them. When Office application files open in Protected View, some functionality is unavailable. The process of dragging the file to a new location and then opening it takes more time than simply double-clicking the file to open it, modifying it, and then saving it to the same location. For these reasons, administrators may receive some complaints from users potentially confused about how to modify files originally only available to them in Protected View.