There is some odd "bug/feature" in Outlook 2003 even with latest filters. Very often a couple of the spams get through to the inbox, but that's not so surpising as this: There is no text, images, links, anything. The whole post is empty. I am not sure is this caused by the filter or what, but i get these couple a day. Either way, why would i want to receive empty mails anyway and second, if the filter cleans it up and makes it empty, why not just get rid of the whole thing.
It may be caused by some combination of settings. I have setup my Outlook 2003 to show the messages as plain text, no images etc.
Other thing is, very obvious fraud emails get through, i got a ton of Citibank fraud mails just recently. The filters should look if there's obvious spoof going on like: http www.citibank.com <realurl:http some.fraud.com>
I would just filter all mails with such blatanly obvious spoof attempts.