There is an option about compacting.
I don't have it enabled so I don't know what it does.
I now have over 23,000 e-mails between my Deleted and Sent folders in Outlook Express v.6 (XPsp2), and for the last few months, every week or so, I get a message asking if I want to free up disc space with compacting. This compacting function has corrupted my Inbox three times now, and sent the entire Inbox to the fifth dimension, not retrievable in any way. I've found that I have to close every open program (including IE 6) to prevent this file corruption, and even then I get 3 or 4 messages during the compacting process that tells me that OE is being used by another program during the compacting, and I have click OK to continue the compacting. If I try to cancel the compacting function, it asks me to compact every time I try to close OE. I've not found a way to disable this compacting annnoyance. Anyone else figured out how to do this? I have a 160GB internal HD and a 500 GB external HD, and saving space on my discs is not a concern.