[Baypiggies] Challenge/Response email systems

Dennis Reinhardt DennisR at dair.com
Fri Jun 16 18:29:50 CEST 2006

At 08:58 AM 6/16/2006, you wrote:

>4. Is there anything as bulletproof as CR, but without the problems?
>And I am not asking about
>better filters (that's just an ongoing battle against better spam).

I think so and have implemented such in my latest version of SpamAI:

         Guilty until proven innocent

Only whitelisted email is directed to your inbox.  The rest is reviewed or 
ignored as you see fit.

Because this algo and C/R are both explicit whitelist systems, they are 
equally bulletproof.

Now on to "the problems"...  A C/R "shares" *your* spam problem with people 
who send to you.  Now, there is going to be an asymmetry in who finds the 
message valuable.  Consider this table based on who finds the message 

hi importance to sender, lo importance to receiver
The sender does the work to go through C/R and the recipient gets a message 
they are not interested in.  Sender is irritated but so what?  - for C/R

low importance to sender, lo importance to receiver
message is lost. + for C/R

hi importance to sender, hi importance to receiver
The sender does the work and recipient receives message but at the cost of 
irritating sender on something both consider important.  Both + and - for C/R

lo importance to sender, high importance to receiver
The message is lost and the sender is *really* irritated. - for C/R

Including the ambiguous case, there are 3 - and 2 + for C/R.  C/R works 
less well when there is an asymmetry in the importance of the 
conversation/message.  I think the sender's responsibility ends when they 
send their message.  From that point forward, it is the recipient's sole 
responsibility to act/not act.


| Dennis    | DennisR at dair.com   |
| Reinhardt | Powerful Anti-Spam |

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