Let's look at a few stats on my spam:
- Spam conversations in the last 30 days: 50,000
- Other conversations in the same timeframe: 745
- Percent of conversations that are spam: 98.53%
- Percent of conversations that are legit: 1.47%
- Average time between spam messages: 51.8 seconds
I'm glad that Google has such an amazing spam filtering system, or else email would be completely unusable for me. (As an aside, I'm taking a class on machine learning right now, and it's cool that Google uses advanced machine learning techniques to implement their spam filtering. All of that nerdy computer science stuff I'm learning about is quite useful in real life.)
How did we get to this point? After all, back when I started using the internet in 1995, Spam was almost unheard of; today I have received 37 spam messages since I started writing this blog post. It all boils down to two things: motives and methods.
For spammers to be successful, they need a market of people who will buy their products. If no one ever clicked on a link in a spam message, it seems pretty obvious that it wouldn't be worth it for spammers to continue. However, there is unfortunately some small, clueless proportion of the population who are in the market for "Male enhancement", "New collection of Swi$$ R0lex", or "Mic.rosoft Win.dows Vista U1timate" and think that responding to spam is a good way to get what they want. I have yet to meet one of these clueless people in real life, but they must be out there, or I wouldn't be receiving spam. It's simple economics.
So what has changed since 1995?
- More people use the internet now, so it's a larger, more attractive target to potential spammers.
- The average internet user is less computer-savvy (and maybe less everything-savvy) now than in 1995.
These days, your grandma, Joe Sixpack, my baby brother, and everyone else in the developed world is on the internet. Now, instead of marketing to a group of scientists and engineers, spammers are marketing to a pretty broad cross section of the population. Both the size and the gullibility of the potential market have increased.
Let's do a little cost-benefit analysis to look at the economic incentives for sending spam. Let's estimate how much the bandwidth to send all of that spam might cost. We'll focus only on the top 3 web mail providers (Yahoo!, Microsoft, and Google), ignoring the vast number of other email accounts out there.
- There are about 600 million web mail accounts in the world.
- If every one of them receives spam at the same rate that I do (which I admit is probably a little high), that's about 30 trillion messages per month, or an average of about 11 million spam messages per second.
- If each spam is about 1KB in size (seems about average, looking through my spam box), then that's about 85 gigabits of spam per second.
- A quick internet search found a site that lists wholesale internet connection lease rates. They charge $15,000/month for a 622Mbps OC-12 line.
- Even if we assume a 50% discount on line lease rates since the spammers would be using such massive amounts of bandwidth, that still comes out to 138 OC-12 lines, which would cost $1 million/month.
1 message in 15 million.
In other words, if one person in 600 responds to one of their 50000 spam messages a month, they provide an economic incentive for spammers to keep spamming.
Even if spammers have an incentive to do their thing, they still need a way to do it. They won't be able to walk up to most respectable internet providers and say "I'd like to flood the internet with 30 trillion messages a month. Can I buy a little bandwidth from you?". So how do they send spam without being blocked?
They use your computer.
A large percent of spam is sent by organized crime groups. They realize that they can't just go out and buy bandwidth to send spam—after all, who would sell to them? Besides, if they bought bandwidth from one place, it would be pretty easy to block that one place and stop the flow of spam. They would also have to buy millions of dollars of computer equipment to handle sending all of that spam.
Rather than deal with all of those problems, they use botnets to send spam. A botnet is a network of hacked computers, usually running Windows, that is under centralized control. The person controlling the network can have 1000s of computers all across the internet send out spam for them. This offers a couple of advantages to spammers:
- It's really difficult to track and block spam from so many different sources.
- They don't have to pay for bandwidth or servers.
If you've ever downloaded and run one of those fun little games someone emailed to you, or if you've ever run a cool screensaver you found on a shady-looking web site, or if you don't run antivirus and firewall software, or if you don't keep your system patched with Windows Update, or maybe even if you do do all of these things, your computer might be part of a botnet and you don't even know it.
The situation is depressing, and there are no really good technological measures for stopping the flood of spam without drastically changing the way that internet email works. At least Google has some good filtering algorithms.
PS—Here's the current count: