From: "Karsten M. Self" <[EMAIL PROTECTED]> As I have:
http://kmself.home.netcom.com/Rants/challenge-response.html
I might add that I myself use a mix of whitelisting and spam filtering (via SpamAssassin) to filter my own mail with a very high level of accuracy, in terms of true positives, true negatives, false positives, and false negatives. Namely: better than 98% true positive (filtered spam),
That's good, and spamassassin is definitely a nice tool especially with the bayesian filtering and vipul's razor modules.
less than 2% false negative (unfiltered spam)
That's bad, I don't know about you, but as an administrator, I get ALOT of email, often as many as thousand a day or more (counting spam, around 100-300 legit) and a 2% false negative rate would give
me nearly 20 spam messages a day, which is highly annoying, but that's a problem I could live with if it weren't for the next issue.
99.98% true negative (unfiltered non-spam), and less than
0.02% false positive (filtered non-spam).
That's totally unacceptable, at that rate I could lose as many as 5-10 legitimate emails a week and that's just for one person, if you figure a more reasonable email volume for the rest of our employees at about 1/3 that rate you're talking hundreds of lost emails every week. Even if my numbers are two orders of magnitude too high, that would still be at least one a week, and I can tell you that my boss' acceptable loss rate is ZERO, EVER, FOR THE LIFE OF THE COMPANY. Which just can't be achieved using spamassassin alone, unless you want to manually go through all your junk mail, in which case why are you bothering in the first place?
While some C-R proponents claim filtering doesn't work, it clearly does.
In my opinion, no one spam fighting system is effective by itself, a good system should take advantage of all of them, to try and mitigate the worst features of each.
Chris Berry [EMAIL PROTECTED] Systems Administrator JM Associates
"You are not special. You are not a beautiful or unique snowflake. You are the same decaying organic matter as everything else." -- Tyler Durden
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