Here is a simple strategy that can help you deal with spam in Outlook 2003. Using this method you can automatically direct any spam emails you recieve to one folder (i.e Junk or Deleted). It uses a very simple mechanism, in Outlook 2003 it is possible to move email to a folder if it is not sent from someone who's email address is already in one of your contacts folders, you can do this in Tools > Rules and Alerts.

That is not the end of the story, if your anything like me then you probably do quite a bit of emailing and you would find it pretty inconvienent to have to create a contact for everyone you get email from. Well you don't have to, Mapilab have created an Outlook 2003 add-in that will do this for you. It is not free but it is only US$15 and you can get it here. The add-in once installed can be used to process all the emails in a folder that you have already received to create a contact for the sender if one does not exist already. It can then be configured to create a contact (if one doesn't already exist) everytime you reply to an email. I have created an 'Unsorted Contacts' folder where these are put. The only time you really have to delve into your junk mail folder is if you signup to a site that needs to email you to register, then you simply find the message, hit reply and a contact will automatically be created for that address so future emails will get through.

So far this method has worked well for me, it is quite a cheap option and whilst it's not perfect it makes my life a lot easier.