To register a clickable URL:ms-outlook protocol with your MS-Outlook application, perform the following steps:

1. Open your start menu, then search for “Default Apps” and open it.
2. Into the “Set a default for a file or link type” field, enter MS-OUTLOOK
3. Click on “Outlook”.
4. Confirm with “Set default” 

✅ Note: This example is for Windows 11 and assuming that Outlook was already installed by your administrator on step 3. 

💡The procedure of registering an App may look different depending on your OS version and UI language, but the process remains largely the same.