How Spammers Fool Whitelists - And How to Stop Them

Effectively stopping spam over the long-term requires much more than blocking individual IP addresses and creating rules based on keywords that spammers typically use. The increasing sophistication of spam tools coupled with the increasing number of spammers in the wild has created a hyper-evolution in the variety and volume of spam. The old ways of blocking the bad guys just don't work anymore.

Examining spam and spam-blocking technology can illuminate how this evolution is taking place and what can be done to combat spam and reclaim e-mail as the efficient, effective communication tool it was intended to be.

One method used to combat spam is whitelisting. Whitelists are databases of trusted email sources. The list may contain specific email addresses, IP addresses or trusted domains. Emails received from a whitelisted source are allowed to pass through the system to the user's email box. The list is built when users and email administrators manually add trusted sources to the whitelist. Once built, the catch-rate for spam can be close to 100%, however, whitelists produce an inordinate number of false positives.

It is virtually impossible to produce an exhaustive list of all possible legitimate email senders because legitimate email can come from any number of sources. To get around this difficulty, some organizations have instituted a challenge-response methodology. When an unknown sender sends an email to a user's account, the system automatically sends a challenge back to the sender. Some challenge-response systems require the sender to read and decipher an image containing letters and numbers. The image is designed to be unreadable by a machine, but easily recognizable by a human. Spammers would not spend the time required to go through a large number of challenge-response emails, so they drop the address and move on to those users who don't use such a system.

Whitelists are only partially successful and impractical for many users. For example, problems can arise when users register for online newsletters, order products online or register for online services. If the user does not remember to add the new email source to their whitelist, or if the domain or IP address is entered incorrectly, the communication will fail. Additionally, whitelists impose barriers to legitimate email communication and are viewed by some as just plain rude.

Whitelists are not widely used by email users and administrators as a primary tool to fight spam because of the high number of false positives, and the difficulties in creating a comprehensive list of email sources. Because whitelists are not widely used, spammers typically do not develop countermeasures. As with other spam fighting techniques, whitelists are most effective when used in conjunction with other anti-spam tools.

The Solution

When used individually, each anti-spam technique has been systematically overcome by spammers. Grandiose plans to rid the world of spam, such as charging a penny for each e-mail received or forcing servers to solve mathematical problems before delivering e-mail, have been proposed with few results. These schemes are not realistic and would require a large percentage of the population to adopt the same anti-spam method in order to be effective. You can learn more about the fight against spam by visiting our website at www.ciphertrust.com and downloading our whitepapers.

Dr. Paul Judge is a noted scholar and entrepreneur. He is Chief Technology Officer at CipherTrust, the industry's largest provider of enterprise email security. The company's flagship product, IronMail provides a best of breed enterprise anti spam solution designed to stop spam, phishing attacks and other email-based threats. Learn more by visiting http://www.ciphertrust.com/prod ucts/spam_and_fraud_protection today.

---

What To Do When You Get Spam

When you go to your mailbox and find pieces of... Read More

Bayesian Spam Filters Explained

In a word Bayesian spam filters are "intelligent". Bayesian spam... Read More

How To Stop Spam (Especially If You?re Already a Victim)

Spam. Those annoying, time-consuming emails that clog your Inbox and... Read More

Lockspam Free 3.0 Released!

6 August, 2004: Polesoft Inc., home of Professional anti spam... Read More

Edating Readers

One of our Australian clients sent out a campaign using... Read More

How to Write a Privacy Policy

A Privacy Policy can be defined as the policy under... Read More

CAN-SPAM Basics

I. BACKGROUNDThe CAN-SPAM Act of 2003 (Controlling the Assault of... Read More

Take Back Control of Your Inbox: Eliminate Annoying and Potentially Harmful E-mails

Are you tired of spam stealing your time, your money,... Read More

Learn Simple Strategies That Will Stop Spammers From Bombarding Your Inbox!

Spam filter is the solution that most people resort when... Read More

The Trouble With Spam Is....

Each day we all face the same challenge. Spam. It... Read More

Spam eMails Are Not Just Annoying - They Are A Main Distributor Of Viruses

Why is someone from India, Africa, or elsewhere writing you... Read More

Pst... Pass It On... I Found Out Its a Hoax

When you receive an email telling you about a virus,... Read More

Spam Filters Explained

What do they do? How do they work? Which one... Read More

Stuffing the Spammers!

I'm really, truly fed up with spam. Every day when... Read More

Do Not Spam

The temptation among internet marketers to SPAM is greater than... Read More

The Business Of Sending Spam

You all tear your hair out in frustration every time... Read More

Stop Spam: How To Escape The Spam Hell-Hole

If you're anything like me, you're pretty sick of it,... Read More

Junk Mail Works!

Junk mail works. Why does it work? How does it... Read More

Fight Spam and Fortify Your Web Site with RSS

RSS is the answer to the Spam epidemic of the... Read More

Email Spam and Phishing

It seems like the volume of email spam has doubled... Read More

Beware Of Spam Withdrawals

Q: I am so sick of all the spam that... Read More

What Is Spam?

If you've been around the interenet any length of time... Read More

Why Your ISP Takes Bribes From Spammers

The lifeblood of the spammer is email. They need to... Read More

Internet Theft and Fraud

My friends in the web hosting business have recently informed... Read More

Spammer Stole My Email Address?

Do you get bounced, or rejected emails sent by someone... Read More

20 Words That Kill - At Least When It Comes to Spam Filters

Spam, spam, spam. It's terrible not only for those of... Read More

Winning the War On Spam

For years I didn't worry much about spam.But lately it's... Read More

Having a Bad e MALE Day? Email, Spam, Spam and More Spam

You just sat at your desk, opened your email account... Read More

How You Can Avoid The New Dangers Of Spam

Until recently, spam has been an annoyance, a definite load... Read More

Is There A National Do Not Spam List?

You may have already received a do not spam list... Read More

How to Fight Back BEFORE Youre Falsely Accused of Spam

A friend of mine received a chilling email message from... Read More

Spasms & Spamocidal Mania

Below is a letter I wrote to the following organizations:S.H.U.... Read More

Spammer in the Slammer: Jeremy Jaynes Sentenced to Nine Years

Will other spammers take heed? Don't count on it.Jeremy Jaynes... Read More