A Trial Balloon to Ban Email?

[Bill Frantz]

If you go to an ISP collects model, see how this changes the picture.

At 6:57 AM -0700 5/14/03, Sunder wrote:
>Yes, but how will you stop the spammer from double spending the same $0.25
>micropayment on all of his 170,000 email addresses?  Depending on whether
>you check that there is a payment attached or not, and also check it with
>the bank before delivering it, you'd have already wasted your bandwith and
>possibly have accepted a spam into your mail spool.

ISP receives mail header.  As soon as the coin appears, it:

(1) Check it against the in-memory Bloom filter of already seen coins.  If
it passes, goto collect.

(2) Check it against the local database of already seen coins.  (Because
Bloom filters can give false positives.)  If it is in the database, drop
the mail and the connection.  Result: no mail in the spool, and minimum
bandwidth lost.

(collect) Add the coin to the Bloom filter and to the database.  Collect
the money from the bank.  If the bank says, "double spent", drop the
connection and the mail as above.

Note that this system will work well against spammers who blast out
identical coins to a lot of addresses at an ISP.

Now spammers can engage in a DOS attack against this system by using junk
coins.  It won't help them get the spam thru, and it will be detected when
there is a TCP connection between their machine/open relay/etc. and the ISP
machine.  That will go a long way toward locating them in meat space, so
fraud charges can be brought.

Cheers - Bill


-------------------------------------------------------------------------
Bill Frantz           | Due process for all    | Periwinkle -- Consulting
(408)356-8506         | used to be the         | 16345 Englewood Ave.
frantz at pwpconsult.com | American way.          | Los Gatos, CA 95032, USA



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