I just upgraded from Office 2003 to 2007. I attempt to open an Outlook link with file extension XNK, but I receive the error message “Cannot start Microsoft Office Outlook. The command line argument is not valid. Verify the switch you are using.”
Support for opening such files directly has been dropped in Outlook 2007. The officially supported method for opening those files is by creating such a file and then create an Outlook shortcut to it with the /x command line switch to execute it. Anything but practical as you would now have 2 files instead of 1 shortcut file.
However, we can still make it work as it used to work by some registry modifications. You can download these modifications here. The zip-file contains 2 registry files;
- xnk-x86.reg For 32-bit versions of Windows
- xnk-x64.reg For 64-bit versions of Windows
Execute the reg-file for your version of Windows by double clicking on it. You’ll get a confirmation when it has been successfully added to the registry.
Note 1: For importing this registry file you’ll need to have Administrator rights on the computer.
Note 2: You may need to restart your computer for changes to take effect.
Note 3: By default xnk-files are blocked attachments. If you received an xnk-file and you want to unblock it, read this guide.