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In order to prevent spam, you should first get a glimpse of what it is and how it works. Once these are understood, the methods of preventing spam will be more easily applicable.
What is SPAM
Well, the term actually comes from a variety of canned meat made by a Minnesota-based company which also renamed it’s home town to Spam Town USA. However, in the virtual world of the Internet, the term “spam” has a whole different meaning and it’s not as pleasant as tasting the canned meat.
The meaning of “spam” related to the Internet actually refers to different types of unsolicited messages being sent by abusing electronic mail systems. The most widely used form of spam is known as e-mail spam or e-mail messages which are sent by the thousands and even by the millions to different recipients.
The senders of spam e-mails, or spammers, use these messages to advertise certain services or products, to attract visitors to certain websites or to use stock dump techniques.
In order to send spam without being caught or identified, spammers use different techniques which range from fake sender addresses to using large number of virus infected remote computers (a.k.a “zombie computers”). Databases with thousands of e-mail addresses have become of such a value for spammers that they are now subject of trade on the Internet and are being sold for relatively large sums.
SPAM has numerous negative effects on the Internet such as overloading mail servers, using unnecessary bandwidth and storage space or blocking legitimate e-mail addresses.
How SPAM works
The hole process of spamming starts by collecting the e-mail addresses which will be later used as recipients. Since spam is, by definition, unsolicited, spammers have a series of methods to harvest these addresses and build huge lists of recipients. The most common method used by spammers to obtain large number of e-mail addresses is by using special automated programs (a.k.a “spambots”) which crawl websites and harvest any e-mail address they can find.
Another efficient way of obtaining e-mail addresses is by distributing computer viruses which scan the infected computer’s hard-drives and even network drives in search of any e-mail addresses they can find and which they later send to the spammer’s computer. Some of those viruses have managed to infect a large number of Windows computers and the amount of e-mail addresses they harvested was probably exponential.
Once spammers obtain the e-mail addresses of their victims, all they need now is to start sending them the unsolicited messages. Early on, spammers discovered that if they sent large quantities of spam directly from their ISP accounts, recipients would complain and ISPs would shut their accounts down.
In order to conceal their identities, spammers have started sending their messages from other people’s computers. They do this by spreading computer viruses which, if successfully installed, transform the affected computer into a “zombie computer”. Such a computer may later be used by the spammers to send their messages as if they originated from the zombie computer itself thus directing the investigator’s attention to these computers rather then the spammers themselves.
A specially crafted computer virus (spam virus) can infect up to several hundred host machines creating what is know as a botnet. A botnet can then be used not only for sending millions of messages per day but also for other illegal activities such as denial-of-service attacks. These botnets are as precious as e-mail addresses databases for the spammers and are also a subject of trade. By using botnets, the tracing of spammers becomes much more difficult if not impossible.
Methods of fighting SPAM
With SPAM becoming such a wide spread phenomenon, security companies and Internet Service Providers have though of ways to prevent unsolicited messages being send or ending up in users’ mailboxes.
Usually spam messages are being filtered closer to the recipient’s end rather than at the sender’s end. A common technique of blocking spam is by searching for patterns in the headers or bodies of messages. Unfortunately, this technique can be easily defeated by intentionally misspelling commonly-filtered words.
A more advanced technique of filtering spam uses “Bayesian filtering” which - to make a long story short - relies on word probability to determine if an e-mail message is spam or not. If a message contains many words which are only used in spam, and few which are never used in spam, it is likely to be spam. There are other methods of filtering spam but they do not make the subject of this article.
Finally: How to prevent SPAM
First of all, you should know that there are methods of preventing spam with 100% efficiency, but if you follow the rules below, there is a high chance you will notice a drastically decrease in the numbers of unsolicited e-mail you receive everyday (this applies to new e-mail accounts, as the majority of the rules below are ineffective against spam sent to your current e-mail accounts).
As explained above, spammers need your e-mail address in order to send you the unsolicited messages. To prevent spammers adding your e-mail address to their databases, you need to be more careful about how and here you post it on the Internet. Theoretically, if your e-mail address is written in plain text on a website, there is a chance it will be harvested by one of the spammers’ spambots.
Many websites conceal their users’ e-mail addresses or present them in a way that spambots are not able to understand such as replacing the “@” character with an image, or actually spelling the “@” and “.” character as in “john_smith[at]hotmail[dom]com”.
Before you subscribe to a web site using your email address, you should first check how that site displays e-mail addresses and if it displays them in plain text, you should think again before clicking the submit button.
Of course, this method if not bulletproof and your e-mail address could still end up in a spam database, so another recommendation is to create another e-mail account (you can use a free email service such as Gmail, Yahoo Mail or Hotmail) which you can use for the sole purpose of registering to different websites.
A similar approach is to create a temporary e-mail account just for registering to a website. This account will forward any messages to another account of your choice and after a defined period of time it will become unavailable, so you don’t have to worry about spam sent to this address. spamgourmet.com and spamhole.com are examples of websites providing this kind of services.
Although not mentioned above, another way spammers can get their hands on large number of e-mail addresses is by using chain letters. These e-mail messages can accumulate a significant number of e-mail addresses as they are forwarded to different e-mailing lists. By sending those letters, spammers hope that eventually, the chain will close and the e-mail they’ve sent returns to them together with precious e-mail addresses which they will add to their database.
To prevent the harvesting of your e-mail address by this method, you should ask your friends not to include your e-mail address in the “To” or “cc” fields when sending several copies of an e-mail. Instead, they could add all the recipients to the “bcc” field thus removing any trace of who the actual recipients of the e-mail are.
Event though you currently receive tons of spam to your e-mail address there is still something you can do remove as many as you can after they reach your mailbox. Several anti-virus and security suites have built-in spam filters which scan and remove any suspicious messages thus taking off the burden of manually deleting tens and hundreds of messages every day. This can also be achieved at the e-mail service provider level if they have a spam filter implemented into their e-mail server. An anti-virus software is also important in order to prevent your computer being infected by a spam virus and become a “zombie computer” and part of a botnet.
A more active way of preventing spam is by reporting spam to appropriate ISP so that the spamming can be stopped. Although this takes much more time, it’s more efficient as it stops the evil at its source.
A rather exaggerated method of not only preventing spam but also discovering its origin is to create unique e-mail address for each person or site you wish to communicate with. Eventually, you could have a main account and all the other account can forward the messages to the main account. If spam is received on one of these addresses, you immediately know who leaked or sold your address to spammers, and you can also cancel the affected e-mail address.
Conclusion
The first conclusion that should by drawn is that there is no way of definitively prevent spam. As long as you use your e-mail address there is a chance that it will end up on the hands of a spammer and you will start receiving daily messages about pornography site subscriptions, prescription drugs, purported sexual enhancement products, printer ink cartridges, counterfeit brand name goods, counterfeit software, mortgage offers, fake diplomas from nonexistent or non-accredited universities, and pump and dump penny stocks.
However, if you become a little bit more careful about how and where you use your e-mail address, you will manage to reduce the amount of spam sent to your mailbox.
Oh, and if you are really tired of deleting that dozen of spam messages every day, you should know that, according to Wikipedia, Jef Poskanzer, the owner of the domain name acme.com, is receiving over one million spam emails per day.
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