Outlook Safe Mode is a diagnostic mode that allows you to troubleshoot and resolve issues with the Outlook application. When you start Outlook in safe mode, it runs without loading any add-ins or customizations, which can help identify and resolve problems caused by third-party software conflicts or corrupted files.

In safe mode, Outlook uses default settings and disables features such as COM add-ins, toolbar customizations, and certain advanced functionalities. This mode provides a clean environment for troubleshooting and isolating issues that may be affecting the normal functioning of Outlook.

Common scenarios where Outlook Safe Mode can be useful include resolving crashes, startup issues, freezing, or unexpected behavior of the application. It can help determine if the problem lies with Outlook itself or with an add-in or customization.

To start Outlook in safe mode, you can typically press and hold the "Ctrl" key while clicking on the Outlook shortcut or launch icon. A dialog box will prompt you to confirm opening Outlook in safe mode.

By utilizing Outlook Safe Mode, you can diagnose and resolve various issues, allowing for a smoother and more efficient experience with the Outlook application.