Previous versions of OWA didn't let you look at mail headers. In Exchange 2007, you can. Open a message in OWA by double-clicking on it or hitting Enter, then click on the "Message Details" icon.
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Updated Jul 01, 2019
Version 2.0
Blog Post
Headers must be accessible in some way via webmail. Its an invaluable troubleshooting tool. Having a resizable dialouge box would be nice, but I can live without it since it is really only used in troubleshooting situations, and it will most likely be copy-pasted by the user into a new email to send in to IT support (me). This is especially useful for emails that break outlook and need to be eliminated or evaluated in webmail, but also helps when trying to trace the source of an email delivery problem. I never bother to use headers to determine whether or not an email is spam - in cases where the subject line leaves some ambiguity, I'll just open it and see for myself.
What would be really nice is an automated or intuitive way for users to show the headers to IT. I agree with 100% with Rahul - users don't care about headers at all, but IT does. My biggest non-spam pain would be solved if users could forward emails to me without losing all the header info. A site configurable "Report this email to admin" button would eliminate a lot of steps admins have to go through in the troubleshooting process.
What would be really nice is an automated or intuitive way for users to show the headers to IT. I agree with 100% with Rahul - users don't care about headers at all, but IT does. My biggest non-spam pain would be solved if users could forward emails to me without losing all the header info. A site configurable "Report this email to admin" button would eliminate a lot of steps admins have to go through in the troubleshooting process.