Anyone who has looked for an email anti-spam solution is probably familiar with spam capture rate statistics. You’ve no doubt seen claims such as “Blocks 99.9% of spam” but what the capture rate doesn’t tell you is going to prove even more important to your overall filtering satisfaction.
While some spam campaigns are innovative and can be difficult for various filtering systems to catch, stopping most spam email is not too difficult. The real challenge is NOT filtering the good mail that end users want to receive in the process.
A spam filter’s claimed capture rate means nothing if you do not know their false-positive rate. False positives are good emails caught by the filters and marked as spam. A great capture rate will not be acceptable to the end-user if it comes with a high false-positive rate. The cost of lost opportunities and delayed responses to legitimate mail will exceed the benefit provided by the blocking of spam.
