Content Search not recognising file extensions

Hi,

I use the Content Search feature in the Compliance portal, to search for content in a Sharepoint Site. The filenames are in the following format, FAR0530001.28.A5674.msg

Content Search finds the keyword in the file and lists it as FAR0530001.28.A5674 .This causes the Viewer to fail to display the file (unknown). If the file is downloaded and renamed to FAR0530001.28.A5674.msg, it can be opened/viewed. Is there a way to configure the search, to recognise the filename with its extension

Thanks

Mike