Apple in a support document explains why Microsoft PowerPoint slides appear blank with a white background or fail to render properly in the iPhone and iPod Touch Mail app. The problem’s caused when documents, which’re subject to display size limitations, are converted to HTML Web pages before being displayed on iPhone or iPod. Large images or multiple medium-size images used on a PowerPoint slide result in some not being visible in the converted content. Apple offers following suggestions: Reduce the size of images in any of the slides that failed to render properly and resend to the iPhone or iPod; Convert the PowerPoint file to PDF and resend; View the PowerPoint on your computer using MS Office or Quick Look on Mac OS X v10.5 or later. If you’d like to learn more about size limitations of content viewed on the iPhone or iPod Touch, read up in the Safari Reference Library.