Opening an OFT file without installing Microsoft Outlook is tricky because the format is explicitly designed for Outlook templates. If the user only wants to look at the structure of the message, the best solution is to convert the OFT file to a more popular email or text document format. 

For example, it becomes much easier to open in other email clients or in a web browser if the template is converted into EML, MSG, or HTML formats. Such a template, after its conversion into HTML, is viewable in browsers like Google Chrome or Mozilla Firefox. 

One practical option some users use is Softaken OFT Converter, which allows one to convert OFT files into many different formats and open them without Outlook. After conversion, the file can be accessed normally in another email program or browser (depending on the format you choose).