Microsoft Outlook 2007 has a handy preview tool that will allow you to preview documents (Word, spreadsheets, PowerPoint) from within the mail message, however it lacks the inbuilt ability to preview several popular file formats such as zip files, PDF files, programming source code files and so on.
The lack of previewers for some of the most popular file types was something I could not live with long, with the help of two Outlook add-ins I can now preview Zip files, PDF files and many other file formats from within Outlook.
Another add-in that may interest all users is the sample previewers from MSDN, it adds support for several popular files formats including ZIP, PDF, XML, MSI, BIN, CSV, XPS, and XAML files. Download sample previewers from MSDN.
Hope these add-ins help solve a major problem for many of Outlook 2007 users. If you use any other preview tools, don’t forget to tell us about them.