I recently (4 mo. ago) made the big switch from 'world-o-PC' to Mac. I love the Mac and find there is nothing I can't do in connecting to corporate services just as well or (usually) better.

Part of my shift to Mac entailed embracing GTD (though not causally related) and trying to function more simply and effectively. On my old PC I had a massive hierarchy of folders that existed to hold project specific and general reference email. While ostensibly well structured and organized, the folder hierarchy was unwieldy and boat anchor on productivity.

First, it was difficult to have the right folder for every occasion. Often times a piece of mail didn't fit neatly into a particular folder (i.e. category). E.g. should this e-mail that has bearing on many projects be stored in one of the project folders or in some general reference folder? A lot of email tended to fall between categories and hence folders. The problem was that whatever decision I made as to which folder to file the email, I could never remember where I put it when I actually went to retrieve the email at some later date. So, more often than not, I had to use the Google search plugin for Outlook to find what I was looking for, anyway.

Second, once I put an email into one of the folders of my elaborate hierarchy, I almost never looked for it. It was too much work to go find it and tended to hold emails I should have either properly acted on or deleted altogether. So, my folder hierarchy became like an old junk yard that I was loathe to visit.

All the work put into building and managing the hierarchy and trying to figure out which folder to stick an email in ended up taking time and effort without yielding benefit.

Now I use mail.app with only 4 folders and Mail ActON/MailTags to put things in their proper place:

Respond Waiting For Hold Archive

I have tried to reduce these to three folders, but have found that, given my style of processing, the above four folders work best.

The other thing I have given up on is the quest for a monolithic system that does everything and does it well. Outlook comes close on the 'does everything' front, but falls far short on 'does it well'. I never could get organized in a way that worked for me or that I really stuck with because it was over-engineered. Now, with superior apps for Mac OS, I use kGTD+Omni Outliner (after extensive trials with various apps), iCal, mail.app, and a smattering of plugins (QS!) to make these things work better and together, where possible.

Conclusion: Complicated folder hierarchies encourage clutter and CLUTTER KILLS. :-)