random thoughts on how I can prevent spammers from using my net

[ALAN DORN HETZEL JR <dorn () atlanta net>]

I have been trying to figure out ways to prevent spammers from using my
net as a sending location (even once).  If most spam is sent from
throwaway dialup accounts, how would a daily limit of #arbitrary-number
of emails sent, with a charge of $0.05 (or other number) per excess
e-mail...?   The arbitrary-number might be 1000 or so, plenty for most
legitimate uses.  Since we get credit card numbers from our dialuo
customers, if we do get a spammer, and they send, say 100,000 emails
in a month, we subtract their allowance of 30K or so and bill them 
$3,500  (70K * $0.05) for excess....  

If we make the terms and conditions obvious, and get a signature before
activating the account, it won't take very many occurrences before word
would get around that SPAM can ocst as much as paper junk mail to send

Thoughts?

-Dorn
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