Spam is a strange beast. It costs so little to send yet it costs the world so much to receive and deal with it.

Unfortunately, it costs virtually nothing to send spam which is why there's so much.

Spam is sent in various magnitudes. Some spammers obtain a simple dial-up Internet account for a free trial period or use a stolen credit card to obtain the service. At no cost to them they then send out thousands of spam per hour. Even if they pay for their dial-up service, that may cost them only $10 per month. If we assume that they can send spam to 5 addresses per second, that's about 18,000 spams per hour, 432,000 spams per day, or about 13.4 million spams per month. All on a $10/month dial-up account.

Of course, the full-time "serious" spammers often obtain full high-speed Internet access. They may have as much bandwidth as a small-sized ISP. This may cost them, say, $2000 per month but they easily can send much, much more spam. They can have a network operation center with a dozen or more machines cranking out spam 24 hours a day at high speed. Some of these spammers have reported being able to send out over 100 million spams per month.

If we assume a $10/month dial-up account can send 13.4 million spams per month it can be calculated that sending a single spam costs about 0.00007 cents. That is, it costs about one penny to send out 14,300 spams.

As you can see, sending out spam is cheap. About the only thing that keeps spamming from being essentially free is the fact that they are often closed down by their ISP's when they are discovered to be spamming, and the occasional threat of a lawsuit from an unhappy recepient or even being prosecuted for using stolen credit card numbers.

Someone has to pay for spam, and as the section above illustrated it's certainly not the spammer. Unfortunately, it's us--the receivers of spam-- who pay the cost. But how much?

First, spam uses bandwidth. Internet providers are commonly charged $2 per gigabyte of data transferred. If a typical spam message is 3k in length that means that every 333,000 spams cost $2 in bandwidth. That may not sound like much, but considering that there are currently about 10 billion spams being sent per day that's costing Internet providers $30,000 in bandwidth alone per day. That cost is, of course, passed along to you either as a higher Internet bill or as decreased performance at your ISP.

Second, spam requires the attention of ISPs. They must attempt to filter it, respond to customer complaints regarding spam, and otherwise devote time to spam that could be better spent improving customer service or the technical quality of their ISP. This may require one or more additional customer service representatives even at small ISPs, and many many more at larger ISPs. The salary and related benefits of a customer service representative may be $40,000 per year or more. Again, these costs are passed on to you as a customer.

Finally, probably the most significant cost of spam is the cost to the receiver dealing with it in terms of their time. Many users--especially in businesses--leave their email clients open all day such that when a new message arrives they are immediately notified. Generally, you immediately check the email to see if it's something that requires your attention. Even if it takes only 5 seconds to stop what you're doing, realize the message was spam and delete it, and return to your work, those 10 billion spams per day are costing the world 50 billion seconds in lost productivity each day. That's 1585 years of lost productivity every day.

Just imagine, every week the world loses about 10 millenium in lost productivity to spam. Those that suggest that spam isn't really a problem and that we should "just hit delete" truly don't understand the economics of spam and its cost to world productivity.