[cap-talk] charging for spam. What are the implications

[Karp, Alan H]

John McCabe-Dansted wrote:
> 
> Maybe mail client A could send the email back to the sender B
> (bouncing it would be better, but would need collaboration by the
> email server) with some sort of challenge. 

There is a tool based on a similar idea.  Email is store and forward.
The sending mail server will retry if it doesn't receive an
acknowledgement.  This tool drops an email on the floor the first time
it's seen.  When the server retries, the tool sends the acknowledgement.
Spam servers don't retry because most of the mail they send is
undeliverable.  The result is no spam in your inbox.

So, why doesn't everyone use this tool?  Because the big providers of
email accounts, such as Yahoo and HotMail don't obey the protocol and
don't do the retry.

_________________________
Alan Karp
Principal Scientist
Virus Safe Computing Initiative
Hewlett-Packard Laboratories 
1501 Page Mill Road
Palo Alto, CA 94304
(650) 857-3967, fax (650) 857-7029
https://ecardfile.com/id/Alan_Karp
http://www.hpl.hp.com/personal/Alan_Karp/