At 09:32 AM 6/20/2003 -0700, Dave Crocker wrote:
YS> Lets say a spammers has gained control over a specific IP address for an X
YS> amount of time. He normally sends out 1M messages via that IP. So now to
YS> get around this block, he will send out 2M messages retrying delivery.
This
YS> increases his costs slightly but not to the point where it becomes
YS> unprofitable.
right.
YS> The reason why spammers have not tried this approach yet
YS> become this blocking method has not been widespread.
right.
Lets say to fight this spammer trick email hosts will now reject messages
after 2 times, then the spammers adjusting and sending 3M messages, now
reject value stands at 3 times, spammers send 4M messages, ad infinitum.
This would increase costs of sending email since it would have to be stored
longed and retried longer. HOWEVER, at a certain point (number of rejects),
spamming will become too costly although I think that reject point is very
large. Also, there is a reject point at which the sending MTAs will think
that the message is really undeliverable. The question is where two of
these points intersect. This sounds like something Eric Brunner was
discussing at one point.
This is basically an economic approach - you are increasing the cost of
each sent message by forcing the sender to store it longer and use more
network resources sending it. The same goal would be accomplished by adding
email postage but this approach works without changing the existing
infrastructure. What you are basically doing is imposing cost on ALL users
of the system by forcing them to use network resources multiple times.
Yakov
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