What are some alternatives?
When comparing POPFile and SpamBayes, you can also consider the following products
Spamihilator - The free Anti-Spam-Filter Spamihilator removes more than 98% of spam mails before they even get into your inbox.
Mailwasher - Over 8 million people use MailWasher as their spam filter
Spam Reader - Spam Reader is a free anti-spam add-on for Microsoft Outlook.
Spamfence.net - Professional e-mail security free for private use: With Spamfence.
SpamSieve - Save time by adding powerful spam filtering to the e-mail client on your Mac.
BullGuard Spamfilter - Most people find spam e-mails the biggest nuisance on the Internet.