GTD email management: Temporary Reference information
David Allen advocates the use of email folders such as "_Actions" and "_Waiting For" for managing emails. (I personally use the underscore "_" instead of the "@" symbol because the underscore looks less like an alphabetical character and therefore doesn't distract my attention, yet has the same useful function of moving the name to the top of an auto-sorted folder list.)
Anyhow, another email folder that I've found very handy is "_Temporary Reference" (or "@Temporary Reference"). This is a great place to hold emails that don't require any specific action but are needed for short-term reference -- such as the itinerary for your upcoming business travel, or the automated reply from your colleague whose out-of-office email contains contact info for people with whom you may need to communicate in her absence. When your business travel is complete or your colleague has returned from their absence, you can simply delete those emails during your next Weekly Review (or file them permanently if they must be archived for future retrieval).
Just in case it's helpful, here is my complete list of top-level GTD email folders (using Outlook 2007):
_DELEGATED / WAITING
_DESKTOP TO PROCESS
_READ / REVIEW
_SOMEDAY / MAYBE
(Due to the significant majority of my work that is conducted through email, I've chosen to make email folders for things like Read / Review and Someday / Maybe -- rather than creating a new Task in Outlook every time I receive an email needs to be read / reviewed, etc.)
Hope this helps!