Spamihilator is an anti-spam filtering program that works with any email client. It runs as a local POP server that sits between your email program and your mail server and filters mail based on a built-in filtering mechanism. In addition, you can maintain a blocklist as well as a list of friends (their mail will never be filtered).
The program comes with a nice interface and automatically configures popular email clients (Outlook, Outlook Express, Netscape etc.). You can change the aggressiveness of the filter and also add your own spam words to look for. Spamihilator does not delete the spam right away, but moves it to a recycle bin, where you can review it, restore items or permanently delete them. A good tool, that is safe and easy to use, but needs options to customize or control the filtering process.