[SLL] [SLL} Re: Anti-spam methods

[Bill Campbell]

On Sun, Jul 29, 2007, Glenn Stone wrote:
>On Sat, Jul 28, 2007 at 05:06:58PM -0400, Nicholas Bodley wrote:
>>
>>Fwiw, I just answered a challenge message sent as part of a routine online  
>>business matter. The company didn't recognize my e-ddress, and provided a  
>>link in its message body. Went there, and found a neat, concise window  
>>that asked me to visually copy a number (not OCR obfuscated, either) to  
>>authenticate my reply. Worked very nicely, so I thought I'd pass on the  
>>company name.
>
>Challenge-response kinds of anti-spam don't work very well in corner cases.
>Consider the case of two people attempting to exchange email, each of which
>has one of these critters configured.  The first sender elicits a challenge,
>which runs into his own challenge-response mechanism... *boom*.  Or, even
>simpler, the case of "I need help, I'm getting on an airplane and I need an
>answer by the time I land..."

Many serious anti-spammers consider C/R to be abusive, if not
spam itself because of the blowback produced.

I've found bayesian filters with spamassassin routing messages
above a user-specified threshhold going into a spam folder for
review to be very effective in minimizing the effects of spam
without false positives.  I will drop messages entirely with SA
scores above some high limit, say 20.0 without fear of loss.

Spamassassin also allows one to whitelist senders so their
messages are given a high negative score.

Bill
--
INTERNET:   bill at celestial.com  Bill Campbell; Celestial Software LLC
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