How to Suppress Microsoft Outlook Security Notice Warning for Links with Protocols?

Question

Within several of Microsoft's products, custom protocols exist which can be used to quickly access certain apps or areas within apps. Notable examples include companyportal: and softwarecenter: but the most common example of this is the Windows 10 and Windows 11 ms-settings: custom protocol.

When someone sends an email in Outlook with a link using one of these protocols, they receive a Microsoft Outlook Security Notice asking for confirmation:

The text of the notification reads:

Microsoft Office has identified a potential security concern. This location may be unsafe. ms-settings:notifications Hyperlinks can be harmful to your computer and data. To protect your computer, click only those hyperlinks from trusted sourced. Do you want to continue [Yes] [No]

In certain environments (EDU, corporate etc.) this warning is undesirable and is often a source of confusion for the recipients.

What is the correct process for properly marking these Microsoft protocols as Trusted Locations, or "safe" in both Classic Outlook and New Outlook on Windows so that these types of links (for example, the Settings app) will simply work without displaying this and any other prompts like this?

Answer 1

Hi @JuliusPIV

Welcome to our forum!

Based on my research, this appears to be a known issue that occurs after installing the December 12 security update for Outlook desktop. The Outlook Team found issues with the fix while it was being tested in the Insider channels and the fix was pulled back. An updated fix is currently planned to release in the July 9th public updates for Outlook Desktop.

It's suggested that you could temporarily disable the security notice you can use the registry key:

Group Policy registry path:

HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\security

DWORD: DisableHyperlinkWarning Value: 1

(Note: Serious problems can occur if you modify the registry incorrectly. Before making changes, back up the registry to restore it in case something goes wrong.)

More information: Outlook prompts security notice opening .ICS files after installing protections for Microsoft Outlook Information Disclosure Vulnerability released: Dec 12, 2023.

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