how to open pptx, docx in internet information service (IIS 2003) on web site Posted on March 30, 2011 by dpejic Yes, it's just an IIS setting: by default, it will only serve files for which the extension matches a defined MIME type. To allow .docx files to be downloaded, follow the steps: Open the IIS Microsoft Management Console (MMC), right-click the local computer name, and then click Properties. Click MIME Types. Click New. In the Extension box, type the file name extension that you want (in this case, .docx). In the MIME Type box, type application/vnd.openxmlformats-officedocument.wordprocessingml.document Apply the new settings. Note that you must restart the World Wide Web Publishing Service or wait for the worker process to recycle for the changes to take effect. In this example, IIS now serves files with the .docx extension. If you are interested MIME type for .pptx (Powerpoint 2007) is application/vnd.openxmlformats-officedocument.presentationml.presentation