Hi there, thanks again for your response. The answer: In KDE 3.4.0, you go to Configure KMail, Click on accounts, click the 'Receiving' tab, and create a new account. As you do so there is an option to choose disconnected IMAP instead of IMAP. So I deleted my old IMAP account and set up this dIMAP one. It took a fair while to synchronize (on a 512 ADSL connection it took a good ten minutes).
And the result? Now I have what I want! Instant local access to email folders, and because they are local it is possible to apply filters. Which means I can now go out and record all my friends saying 'it's me', convert them into sound files, and associate them with their incoming mail. Sad but cool.
The only question I have is how long it takes to synchronize on an hour by hour basis (I have it set to receive mail every minute) - and also how resource-hungry this will be in terms of processing and/or bandwidth. Does anyone know?
Thanks anyway, Will