"Getting email to zero is a challenge for me. I have home PC files set up (@action, read/review, Calls, etc) and a paper based GTD system. I am able to get my in box emails processed into the appropriate folders, however, the actions, read/reveiw, and call folders never seem to get to a zero state. Any suggestions?"
I don't think that you should ever expect these to get to a zero state, any more than you should expect your action lists to get to a zero state. Getting your Inbox to zero is, IMO, about getting your _Inbox_ to zero - looking at all the new emails, processing them, and deciding what actions (or potential actions) are called for. Once an email hits @action, Calls, whatever, it's processed, and it's out of the Inbox. Those folders are now support to your action lists - in fact, they _are_ action lists - so they can't be expected to go to zero.
Now, I am a bit fuzzy about read/review. Does this refer to emails where the action really is read/review (as in, "Could you please review the latest revision of this document?" or "New HR family leave policy enclosed.")? Or are they emails that you haven't decided what to do about? If it's the second then, yes, I'd say that they are effectively still in your Inbox, and you need to process them into your system before you can say that your email Inbox is at zero. (Though processing them still might consist of writing an action "Spend ten minutes deciding what to do about complaint from Judy Jones, email 10/1/2010.")
That said, with email the distinction between unprocessed and processed items can be quite fuzzy, and for that reason, I don't use email folders as action lists. When I process an email, I extract the potential actions, issues, notes, whatever, and put them in my main GTD system (in OmniFocus, in my case), and then archive the email. I may process those items into actions or projects on the spot, or they may sit in my OmniFocus inbox, waiting for processing.
For example, if an email comes in saying, say, "Could you please review the latest revision of this document?" then I put a note in my OmniFocus Inbox saying, "Email from Sharon, 10/1/2010, requesting review of Widget Document v2.7.". And then I dump the email that triggered that note into the unsorted archive of all the email from the entire year, because the note contains enough information to allow me to easily find it again.
The only time that I sort my email into folders is when I'm working on a task that uses multiple emails as source material and I don't want to have to search for them repeatedly - for example, if I'm figuring out budget spent and I have a bunch of weekly expense emails. Then I put _copies_ of those emails into a folder, do the task, and then delete the copies when I'm done. But that's project support material, not action management.
All of this means that I never, ever have to read an email again until I'm ready to work on that action. Scanning one-line actions repeatedly, when deciding what to work on, is a lot faster than scanning emails, where each email has to be displayed, and may be cluttered up with greetings and discussions and more than one actionable issue. Once I've identified and extracted the issues included in an email, I never want to have to do so again.