SPAMfighter works with Microsoft Outlook and Outlook Express. Spam is identified with a list from other users. Every time you mark a message as spam everybody else with SPAMfighter has it automatically marked and deleted.
You can create a whitelist with SPAMfighter so that emails from people in your address book will always get through.
The SPAMfighter website has a running total of the number of emails processed and the new users who have joined the group.
SPAMfighter is free for home users. Note that there is a Professional version available which offers even more protection, such as an advanced filter, the ability to remove the Spamfilter footer added to your outgoing emails, commercial support and much more.