All the spam I am getting in my inbox has made me look into some more effective antispam tools. While googling for more information, I came across this article about SpamAssassin. It looks good so far. Here is the article in full, written by Scott Sidel:

Spam isn't just about deposed Nigerian dictators who want to send you millions of dollars. Spam emails often contain malicious code, viruses, phishing attacks, and drive-by Trojans -- not to mention some inappropriate content. One of the best weapons available to defend your systems against spam is the open source software SpamAssassin.