Programmers and developers have an Outlook Reading/Preview pane option, but there’s a catch.
Windows Preview Handlers http://previewhandlers.codeplex.com/ has preview plugins for a range of programming source code.

It gives some contextual colorization to the code, making it easier to read.
- ActionScript .as
- ASPX .aspx
- C# .cs
- CSS .css
- Diff .diff, .patch
- DOS .bat, .cmd
- JavaScript .js
- Ruby .rb, .rhtml, .rjs
- SQL .sql
- VB .vb
That’s great except that some of the file types / extensions are blocked automatically by Outlook. We’ve underlined the blocked attachments.