[Mailman-Users] spam, spamcop and mailman moderation

stephen at xemacs.org stephen at xemacs.org
Sat Nov 11 02:23:32 CET 2006

Patrick Bogen writes:

 > Personally, I'd like to see hashcash become widespread, but I guess
 > that'd be hell for a mailing list.

As I understand it, hashcash is just a totally unprofitable use of
cycles, which is bearable for personal mail, but substantially
increases the burden on mass mail.  While such waste for the purpose
of creating incentives is often effective, in this case I believe it
is not for three reasons.

First, spamming is a business, it has revenues with which to defray
such costs.  My project does not; if hashcash cycles becomes annoying
to my host, I'll just stop sending to hashcash users.  This is an arms
race, it has no physical upper limit on cost.  It is not obvious to me
that in the end the Commies will turn to democracy in the spam arms
race; remember, the Soviet Union broke up because the West
out-businessed them.

The second is that for a bounded cost[1], you can implement signed mail.
With current technology this is something of a cost, but for spammers
it's pure cost, for the rest of us it's arguably a fringe benefit much
of the time.  This is much more effective where usable, because the
signature identifies the sender to some degree, which spammers do not

The third is that hashcash, like challenge-response, has a troublesome
analogy to spamming.  You're setting up a system, or "club" if you
prefer, that uses outsiders' resources *without their prior agreement*
to achieve a personal goal.  If you are in a position to get that
agreement, why not just use signed mail?

The real attraction to hashcash as I understand it is simply that you
don't have to educate users, it can be implemented without them even
knowing it happens.  But until we start educating users, or providing
them systems which make their mail usage appear educated to the
system, the spam problem will not be soluble (where my definition of
solution includes operation of public access mailing lists on a
volunteer basis.).


[1]  At any given level of technology.  Agreed, this cost will
increase over time as acceptable levels of security require more bits
in the keys, but with present technology, this is not a price the
spammers can afford to pay to drive up costs for the rest of us.

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