The best solution for eliminating spam is a hardware solution. If you are an adult webmaster running a large operation, you can now purchase hardware at a reasonable price that will attack the problem of spam. These appliances attack and filter spam using a variety of different methods.
One method used by CiperTrust is to log each IP address and, over time, rate the probability of an IP address sending spam. This also is accomplished after you buy the appliance by connecting to a database of worldwide spam servers that the company maintains. With the CiperTrust product, you also can control the rate at which questionable IP addresses can send email.
Mirapoint’s MailHurdle appliance uses another trick to find bogus IP addresses. This product will send an SMTP retry message to the original server. This is an effective method because most dedicated spam servers are not set up to retry. Another advantage of this method is that SMTP retry messages, even if handled, require extra work from the spam-bot servers that deluge the Internet with email. This method also allows for a cost-based system to rate the probability that a certain IP address or even a certain email packet is spam.
Another strategy employed to identify spam is used by Thumbleweed’s MailGate Edge. Mailgate stops mail or flags mail that contains invalid users that are not listed in your server’s active directory. This product also identifies senders whose IP addresses do not match the alleged domain that the email was sent from. This feature is common among spam-blocking software and cuts down greatly the effectiveness of fake proxy emails.
Using these appliances to protect your mail server can reduce your email load by more than 50 percent. They also are useful at thwarting DoS (Denial of Service) attacks. A DoS attack is when a malicious user overloads your web and/or email server with useless requests. These appliances will detect high activity and stop it. This is accomplished by identifying nonstandard SMTP communications and repetitive communications that are the work of a spam bot.
Hardware-Fighting Spam
The spam-fighting hardware appliances that we have looked at range in price from $5,000-$10,000. If you have only one lightly used mail server, you might seek a software solution. But if you are a large operation that uses many mail servers at one location, these products can more than earn back their cost by saving you time and the need to purchase additional equipment as unwanted mail volume increases.
The simplest software solutions, which are either free or usually under $100, rely on a white list. A white list is simply a list of domains and/or users that are allowed to send email to your company. This solution is only good if you want to send and receive email to a relatively small number of people.
Norton and McAfee both entered the spam filtering market with software that is based on blacklists maintained by these companies. So, for instance, if a server in China sends out a huge amount of email, this information is stored on a central server, and your software will then block email from that domain. The problem with these solutions is that they sometimes require an annual subscription to the vendor’s spam database.
Newer spam algorithms use the Bayesian Method to filter spam. This simply means that the probability of an email being judged as spam is based on a set of variables. These variables might be facts such as the IP address, domain or word content. The advantage of this method is that the software can learn. If it makes mistakes by blocking useful mail or by allowing through spam, it will change the weight of certain variables that led it to that decision in the future.
Even certain freeware spam filters such as Mozilla’s email component of their browser and Eudora use a Bayesian filter to trap spam, meaning you can teach your email client how to detect spam. The advantage of these mail servers is they also run on multiple platforms, not just Microsoft Windows.
Outlook Express does not use Bayesian filters. This makes Microsoft’s default mail-reader one of the worst spam-blockers on the market. Yet don’t fret Microsoft users, there are many third-party solutions that will monitor and block spam that is received by Outlook Express.
SpamBully is one such type of software that you can use with Microsoft’s Outlook Express. This software uses Bayesian methods and will even automatically report detected spam to the FTC. To get a free download of SpamBully, visit Spambully.com.
Free Blocker
For a free spam blocker that works with Outlook Express, check out: Spambayes.sourceforge. net or SpamAssassin. apache.org. These software
offerings are free and use the Bayesian method, thus allowing you to teach them how to detect your spam. They also run on a variety of different operating systems.
For general information on the technical side of blocking spam, you should visit PaulGraham.com/paulgraham. This site was founded by Paul Graham who pioneered the use of Bayesian filters to detect and block spam. The website provides a comprehensive index of current spam software and a database of spam offenders.
Many of us have come to accept spam as if it was dust on our front porch that we need to sweep off every morning. This attitude might be logical for an individual, but if you are an adult webmaster who receives a lot of email, you need to attack the problem of spam. If you do, the rate at which you purchase hardware and the lost man-hours from spam will decrease, thus saving you large amounts of money.
