A spam filter is software that identifies and removes junk mail, which can contain malicious code or phishing scams. It compares inbox parameters to configurable rules and can be installed on servers or personal computers. Bayesian statistical methodology is the most popular type of filter, which “learns” from its mistakes and uses a white list to protect against phishing. Many filters are available online with a free trial period.
A spam filter is a software program that sorts your incoming mail to identify and extract junk mail, also known as spam. It can be installed on an Internet mail server, private network server, or personal computer. Spam is not only annoying, it can be used to spread malicious code such as viruses and trojans and to perpetuate phishing scams. For these and other reasons, a spam filter is a great way to protect a computer or network and get rid of junk mail.
To detect spam, the filter compares parameters in your inbox with configurable rule lists. For example, it can be set up to check the subject header of incoming mail for terms associated with pornography, pharmaceuticals, and other common spam products. The sender field could also be filtered for IP address ranges associated with spammers or marketers.
Over the years, spammers have become more sophisticated in their attempts to pass junk mail past spam filters. Spam often includes innocuous or even personal subject titles such as “Hello!” or “About your request”, making it difficult for a general ISP filter to distinguish spam from legitimate email. Therefore, some spam is still transmitted from Internet mail servers to connected private networks and end users.
For this reason, many network administrators install a spam filter on their business or corporate network, as well as end users at home. In these cases, the filter can be highly configured to catch junk email that gets past the more generally configured programs found online. Like other software programs, spam filters are not all created equal. Currently, the most popular is an “intelligent” program based on Bayesian statistical methodology. Compare incoming mail against a set of user-defined rules, then identify spam based on mathematical probabilities.
In the simplest configuration, a spam filter passes junk mail to a spam folder and legitimate mail to your inbox. The user can review assignments and correct errors. The program will remember the corrections and avoid making those mistakes in the future. In other words, a Bayesian program is “taught” what to look for and “learns” from its mistakes. Before long, the filter will make few mistakes and be able to function with virtually no users. A popular free spam filter boasts a near-perfect record after an initial “training” period.
A good filter will also use a “white list” to provide protection from phishing schemes. People who do online banking, for example, can whitelist the correct address of the bank’s website. The spam filter will check your incoming mail for incorrect or similar addresses and reject them as phishing attempts.
There are several spam filter programs available online, most with a 30-day free trial period.
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