characteristics of spam filtering methods
Method | false Neg. | false Pos. 1 | false Pos. 2 | remarks |
conservative DNSBL (against top known spammers) | 15% | 0.1% | 0.01% | |
aggressive DNSBL (against potential spammers) | 7% | 2%~10% | 1%~3% | |
Banning Servers from Policy-Based Netblocks (avoid all zombies) | 25% | 0.1% | 0.5% | |
content keyword triggers | 3%~15% | 1%~3% | 1%~3% | |
content keyword Bayesian pattern filter | 2%~10% | 0.5%~2% | 0.5%~2% | |
content type ban policies (scripts, forms, etc.) | 99% | 15% | 0.1% | mainly affecting automated email, such as order status notification; and newsletters. |
Challenge-Response White-List human test | 0.5% | 100% | 90% |
Points to remember: