(The following is from the TaCoS I intend to use when I finally convert my BBS into a sort of mini-ISP. Some ISPs may wish to copy at least the basic concept of fining spammers, though I realize that this particular system is a mite complex. A similar approach cleaned up Earthlink, formerly a well-known spamhaven, nearly overnight, and is now working wonders even at Netcom, second only to AOL in willful cluelessness among both users and employees (at all levels, in all departments).)
Give A Damn, Don't Spam! This is defined as the sending of bulk unsolicited email (whether commercial, religious, political, or whatever), OR posting the same (or essentially same) article to Usenet too many times (see below for definition of "too many"). Do not spam from here, nor about here, such as (but not limited to) about your web or ftp site here, or soliciting replies to spam here (including by soliciting replies to an address that gets redirected to here). In short, do not make any connection whatsoever between spam and here.
The penalty for spamming is a medium-dependent fine (see below), plus additional fines of $10 per complaint received and $100 per man-hour of staff time spent dealing with your mess (including posting cancellations, dealing with complaints, etc.), with a $200 minimum total.
Newsgroup spamming is determined by the famous "Briedbart Index" or "BI". This is calculated by summing the square roots of the number of newsgroups it is posted to, each time it is posted. You may not reach a total BI of 20 within a 45 day window. Note that if a post does this, it is generally accepted practice that anybody may cancel it -- and someone likely will -- and be held generally blameless. Note that the content of your post, including whether or not it was commercial or on-topic, or in violation of any of our other newsgroup posting policies, is completely irrelevant, for both the cancellation and our fine; the only requirement is that the content be essentially the same. The meaning of "essentially" is at our discretion.
The medium-dependent fine for newsgroup spamming is fifty dollars per BI point. For example, a post sent six times to 25 newsgroups gets a BI of thirty (five (square root of 25) for each time). It therefore incurs a total fine of $1500 (fifty dollars, times thirty BI points). It does not matter whether any of the newsgroups are duplicated. Furthermore, your post will be cancelled.
The medium-dependent fine for email spamming is much simpler: one dollar per address you sent it to (regardless of their validity). For example, an email sent (or attempted to be sent) to 1000 email addresses means a fine of $1000.
All costs incurred in collecting these fines, including (but not limited to) attorneys, notaries, courts, collection agencies, long distance phone calls, postage, etc. are at your expense.