The Linux community - nearly 29 million platform users - has been plagued for years by spam which, according to industry statistics, is dramatically on the rise. Despite relentless efforts to stop it (including billions of dollars spent to develop anti-spam solutions), spam continues to infiltrate our in-boxes every day. Not only does it cost consumers and businesses precious time, money, and resources, but it also represents a huge security risk since many spam sites infect individual computers and corporate networks with viruses or spyware.

Unfortunately, existing anti-spam solutions don't solve this grave problem, but try to hide it. These solutions are reactive and merely try to filter spam after it arrives in the user's mailbox. This passive method of defence does absolutely nothing to stop spam from coming in the first place. As a result, Internet users are losing faith in e-mail and are turning to other methods of communication for trusted sources of information - IM for personal communication and RSS for subscription-based content.

The only way to help users and enterprises to reclaim their e-mail experience is to identify and address the root cause of spam - the spam economy. Fighting spam and winning the war involves a proactive community-based approach that focuses on spammers' financial incentives, which makes removing illegitimately gathered e-mail addresses not only a concern, but a priority.

This article will address how Linux professionals and corporate IT managers, who are seriously evaluating and deploying Linux-based systems, can take a more aggressive approach to fighting spam and, ultimately, reclaim their e-mail experience.

What Motivates Spammers in the First Place?
To understand the impact and potential consequences of spam for Linux users, it's important to identify what motivates spammers to send unsolicited, bulk e-mails in the first place. We can do this by examining a typical "spam cycle."

A typical spam cycle includes the following steps:

1. E-mail address collection: also known as harvesting - is a process in which the spammer retrieves millions of e-mail addresses that can be sent spam. The one-time cost of a mailing list with millions of addresses is typically less than $60.
2. Spam-site creation: the spammer creates an online store in which prospective customers can place orders, following the spam-driven campaign. A specific "spamvertised" site remains online for the duration of the campaign. Designing a simple Web site can cost a few hundred dollars, and the monthly hosting fee from a spam-friendly ISP amounts to another few hundred dollars a month.
3. The "spam run": the process in which the spammer sends out millions of e-mail messages as part of a specific campaign. Sending spam from compromised computers ("zombies"), a very common practice, incurs no costs at all.
4. Revenue generation: with the campaign on its way, and the online store live, the spammer sits back and counts the money coming in. Assuming a 0.01% sales conversion rate on one million e-mails, a spammer's gross profit can range from $3,000 (say, a porn Web site subscription), to $10,000 (sex-related products) or even $150,000 (home refinancing) per campaign.

Although spam is certainly an appealing business (at least from the spammer's perspective), it's a great annoyance to e-mail users in general, creating immense losses in productivity costs. In the last few years, despite significant efforts to fight spam, spam volume actually increased to upwards of 75% of all e-mail traffic. Another 10% is composed of phishing expeditions (scams imitating known brands to fool users into giving their account details) and viruses aimed at creating networks of zombie computers to facilitate spam sending.

Are Filters the Answer?
Unfortunately, most anti-spam solutions that currently exist today are reactive and merely try to filter spam after it arrives in the user's mailbox. This passive method of defence may keep users from seeing that spam, but does absolutely nothing to stop it from coming.

In fact, filters have actually been known to introduce their own set of problems. Being an automatic sorting technology, filters can confuse spam and legitimate e-mails. If a spam e-mail passes through the filter (known as a false negative), the user wastes time seeing and deleting the message. If a legitimate e-mail is tagged as spam and doesn't reach the intended recipient (known as a false positive), the result is a lost business or communication opportunity. In general, filters reduce the reliability of e-mail as an effective business communication tool.

Unfortunately, filtering doesn't impact the spam economy. It just encourages spammers to innovate and invent new ways to bypass filtering schemes. Spammers are also inclined to send even more spam since they know that filters are blocking a large percentage of their insidious traffic.

Taking Action in Court
In January 2003, the U.S. government stepped forward and enacted the CAN-SPAM Act. The law defined the guidelines for sending unsolicited commercial e-mails such as including a valid return address and a working opt-out link in each message. The CAN-SPAM Act also outlawed certain practices such as address harvesting and the use of "zombies" for sending mail.

Almost three years after CAN-SPAM was passed, it has done little to stop spam, although several industry giants, such as AOL and Microsoft, have been aggressively bringing spammers to court for CAN-SPAM infringements. Legal efforts to bring spammers to court do impact the spam economy, at least for those spammers charged. However, the number of spammers brought to court has been very small. In general anti-spam laws are extremely hard to enforce because of the global nature of the Internet and spam operations.

A Proactive Community-Based Approach to Fighting Spam
Before spam, there were telemarketing calls. In response to this growing problem (and annoyance), the U.S. government created the "Do Not Call" registry, offering people a choice and some freedom - they could join the registry and stop getting telemarketing calls altogether, or they could opt-in and continue to get them. Similarly, the CAN-SPAM Act called for the creation of a national do-not-spam registry that would stop spammers from sending unsolicited e-mails to registered e-mail addresses. It was later decided that the government couldn't enforce such a registry and so it wouldn't serve the purpose.

Taking the lead on this initiative, however, Blue Security decided to create a commercial "Do Not Intrude" registry-based solution to fight spam at its source. The Do Not Intrude Registry is an active community-based approach to fighting spam offered free to consumers and small organizations. In December 2005, Blue Security even announced a Linux version of its Open Source spam-fighting software, the Blue Frog. The new offering lets Linux users participate in the Blue Community and register in the company's Do Not Intrude Registry to fight spam actively and safeguard personal and business e-mail accounts through a hands-on community approach.

The Linux version of Blue Frog was created through the contributions of Blue Community members and Linux developers and enthusiasts at large. Blue Frog's visible source program lets users and developers contribute to the development of the Blue Frog client by providing feedback and comments to the company on how to enhance the Blue Frog software and assist in adapting it to other platforms.

The introduction of the Linux version and the cooperation of the developer community are important milestones and significant steps forward for the Do Not Intrude Registry. Most vendors in the anti-spam space (especially the bigger players) don't endorse Open Source and don't supply their solutions for free, so Blue Security's solution is particularly unique and valuable to the Linux community.

Conclusion
Linux professionals and corporate IT managers have long been bombarded by spam, and the threat continues to grow despite relentless efforts and large sums of money (estimated in the billions) to stop it. Compounding the problem, spammers have become craftier, further compromising the rights of e-mail users. Even with federal legislation, the elusive nature of spammers makes enforcement nearly impossible. To combat spam head on, it is absolutely imperative that we change the spam equation. Taking a community-based approach to this perennial problem, and creating an incentive for spammers to stop sending unsolicited e-mails, is truly the only way to take in fighting spam and hopefully one day stop it dead in its tracks.