I've not seen any of the "Sender pays" (camram, money or otherwise) or
"Whitelist" people address this issue...
Assumptions:
1. The vast majority of spam is sent with invalid return addresses (be
they forged or since-closed freemail accounts).
2. A large proportion (approaching or in excess of 50%) of all email is
spam.
Conclusions:
1. First time contact "bounces", whether to ask for payment, or to ask
for a computation, or to ask for "proof of human", get sent to an
invalid address.
2. Someone (most likely your ISP or email provider) has to deal with
the resulting bounce from the receiving domain.
3. A sender pays system doubles the number of junk emails traveling
through the internet.
4. This can only be solved by somehow solving the problem of falsified
return addresses.
5. Solve (4) and you're half way there (perhaps all the way there?) to
solving the spam problem, and you don't need sender pays.
Anyone in the sender pays camp want to address these points?
Matt.
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