Spam filters: Making them work
Spam. It fills our in-boxes, wastes our time and spreads malware -- and it's only getting worse. According to Ferris Research, which studies messaging and content control, 40 trillion spam messages will be sent in 2008, costing businesses more than US$140 billion worldwide -- a significant increase from the 18 trillion sent in 2006 and the 30 trillion in 2007.
In theory, e-mail filtering software and appliances allow "good" e-mail messages to pass through while stopping spam. But the filters can mistakenly allow spam to pass through (a false negative), or they can mistakenly block valid e-mail (a false positive).
Typically, after identifying a message as spam, the filtering software either blocks it or quarantines it, letting the recipient review it later. Although the latter method provides a chance to retrieve false positives, it requires time and effort that users often won't spare.
