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

Dave O'Shea doshea at mail.wiltel.net
Tue Jan 21 01:57:34 UTC 1997

> From: ALAN DORN HETZEL JR <dorn at atlanta.net>
> To: NANOG at merit.edu
> Cc: dorn at atlanta.net
> Subject: random thoughts on how I can prevent spammers from using my net
> Date: Monday, January 20, 1997 2:55 PM
> 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....  

One of the simplest steps that can be taken is to throw a couple simple
filters in the router handling the dialup server, permitting TCP 25 only to
your "approved" mailhost. This step, combined with some rudimentary
procmail work, would put all but the most determined spammer out of

As for zapping their credit card, all they have to do is dispute the
charge. The trick then is convincing your corporate legal department that
some unemployable snotbag from Staten Island is worth the trouble of
slapping with a $25k default judgement. 

> 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

One thing I've considered, (get your rotten vegetables ready, people, this
is a stinker!) would be to set up a "post office"-ish authority, which
would be the only place that you would "accept" mail from. Persons wishing
to have a message "forwarded" by the post office would have to establish
credit, in advance, for some small sum - perhaps a couple of pennies. 

Granted, this leaves all kinds of problems, such as mailing lists and the
like, but it's a thought. There are hundreds of small ISP's around the
country, and the odds of every one of them implementing junk-mail filters
is somewhere between slim and none. I think the only possible source for a
true solution comes in limiting, to a very high degree, who you will accept
mail from.

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