When you are using Outlook 2007 to open a public Exchange folder shortcut that has an .xnk extensions you get the following Error:
Cannot Open File
This is because of the additional security in Outlook 2007 that denies access to certain files automatically. The .xnk extension is one of those file types.
Warning: This workaround may make a computer or a network more vulnerable to attack by malicious users or by malicious software such as viruses. Use this workaround at your own risk.
To work around this behavior, create a link association between the .xnk file name extension and Outlook 2007.
To do this, follow these steps:
Click Start, click Run, type Explorer in the Open box, and then click OK.
On the Tools menu, click Folder Options.
In the Folder Options dialog box, click the File Types tab, and then click New.
In the Create New Extensions dialog box, type xnk in the File Extension box, and then click OK.
Click to select XNK under Registered file types, and then click Advanced.
In the Edit File Type dialog box, type XNK next to the icon, and then click New.
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"
Click OK two times.
Important You should open or download only those .xnk files that are sent by a known source.