Some further info....
I've realised that Norton Utilities is at least partly involved in this. Let's say I delete a big file (900Mb). Initially, Norton put it into a 'protected' area so that it can be recovered later if it was deleted accidentally. This means that the disk size stays the same as it was before, which is fair enough. When I empty my Norton protected files, I get the disk space back.
However, this doesn't seem to hold true for Emails. Let's say I drag 900Mb of Emails from my Inbox into the Deleted Items folder. 'Deleted Items.dbx' increases in size by 900Mb - but 'Inbox.dbx' stays the same size as it was before. Therefore I lose
900Mb of disk space. Emptying the Deleted Items folder at this stage transfers everything to Norton somehow - but it doesn't reduce the size of 'Deleted Items.cbx' Therefore I lose a further
900Mb. I can recover 900Mb now by emptying my Norton protected files. But the problem is that I lost, in total, 1.8Gb - so I'm still 900Mb down!!
Bear in mind that, at this point, my Norton protected folder is empty and the 2 files called 'Inbox.dbx' and 'Deleted Items.dbx' haven't decreased in size. Under Outlook Express's 'File' menu there's an option to compact
these folders. If I do compact them, the size of those 2 files reduces dramatically, but - and this is the annoying bit - my available disk space decreases
. You might think that the data has all been transferred to Norton but it hasn't. If I right-click on my Recycle Bin, both the Unerase Wizard and the Norton protected files are showing as empty. All that data's been transferred somewhere but I've got no idea where it went!!!