In preparation for my column on spamblocking, I invited Karl Denninger, the iconoclastic CEO of Macro Computer Solutions (MCSNet), my internet service provider, to give me his views on spam and spamblocking. Karl is a veteran of many years on the front lines of the Internet and is not known for pulling his punches. Here are his comments:
Spam is a problem for one primary reason: It is inexpensive (read: nearly free, or even completely free in some cases) to send spam to people. For this reason it is favored for marketing things which typically have a low user-response rate, and for which the costs associated with irate consumers are irrelavent (ie: porn, etc). Thus, any strategy to combat spam must fix the actual problem.
You do that with the following steps:
Now you can't always do all three. Sometimes you can't do any of them. There are real, hard limits on system performance which you run up against. Procmail, for instance, can do a fine job of filtering spam. However, it is computationally expensive to use, and as such its a bad choice for this kind of excursion.If you block the spam at the instant the connection to your SMTP server is made, you do not accomplish the necessary goal. Such a block is cheap for the spammer - they move onto the next address in a fraction of a second. But if they are spamming from a dial account, and you ACCEPT the transmission, they now must take the time to actually send it - which slows them down by a factor of 10 or more. The second part of this (no notification) is important as a default as well. Again, the reason is cost to the spammer. You want the spammer to think they got the exposure, when in fact they did not.
Throwing the spam out is obvious :-)
Now, there will be some people who will complain that such a policy is in some way "censorious". And they're right - it is. For this reason it is also important that when practical the network operator give the customer a way to turn off the blocking *if they so choose*.
However, by default, the blocking should be ON. If you default it off, then you fail in the essential purpose - that of filtering out most spam.
To put some numbers to this, MCSNet filters approximately 100,000 spam attempts by email a day. We also filter Usenet spams, and the rate of filtering there typically runs about 300,000 spams daily. No accurate measurement of the amount of email *passed* exists (so a percentage is impossible to determine) but the volume of articles accepted via Usenet is right around 340,000 daily - which means that almost HALF of all Usenet postings are Spam.
If these were passed onward to our customers and internal machines our costs for maintaining those critical infrastructure elements would likely almost double. Needless to say, it is the customer who ends up paying those costs.
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Copyright 1998 Leonard Grossman
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Created with DiDa! 5/2/98 8:34:48 AM.