To do this, follow these steps:
1. Click Start, click Run, type Explorer in the Open box, and then click OK.
2. On the Tools menu, click Folder Options.
3. In the Folder Options dialog box, click the File Types tab, and then click New.
4. In the Create New Extensions dialog box, type xnk in the File Extension box, and then click OK.
5. Click to select XNK under Registered file types, and then click Advanced.
5. In the Edit File Type dialog box, type XNK next to the icon, and then click New.
6. In the New Action dialog box, type OPEN for Action, and then type the following text under Application used to perform action: “DriveLetter:\path\Outlook.exe” /x “%1”
Note By default, the path of the Outlook.exe file is as follows: “C:\Program Files\Microsoft Office\OFFICE12\Outlook.exe” /x “%1”
7. Click OK twice.
8. Click Close.