I receive a lot of mail which is plain text, coming from unix and linux servers who are trying to tell me something. The bad luck is, the company has settled for outlook :( . And outlook breaks these emails. I do get an information bar telling me: “Extra line breaks in this message were removed” but I have to click and click again and it's just not working how I like it. This so-called feature is called “Auto Remove Line Breaks” and is enabled by default in Outlook. To disable it follow these steps:

• Open Outlook.
• On the Tools menu, click Options.
• On the Preferences tab, click the E-mail Options button.
• Click to clear the “Remove extra line breaks in plain text messages” check box:
  

• Click OK two times.

http://support.microsoft.com/kb/287816