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Industry experts predict an even greater increase in the years ahead. Unfortunately, corporate firewalls offer little or no protection. Inbound e-mail often passes through the firewall to your e-mail server without regard for message content, size or address, creating an opportunity for spam and viruses to enter. Spam and viruses cost businesses billions of dollars in lost productivity, interruption of services and wasted or damaged resources. According to Gartner, businesses cannot count on government legislation to help stem the spam and virus problem.1 Instead, they should look to technology solutions for an answer.
Spammers have devised a variety of techniques to bypass firewalls and outdated filters. For example, they insert random text into the subject or body of an e-mail and use HTML in an attempt to outsmart content filters. They "spoof" sender addresses and domains to take advantage of approved sender lists. They create spam or virus hybrids such as SQL Slammer or design scripted attacks such as directory harvest attacks (DHAs) to compile lists of valid e-mail addresses. Sometimes, they even develop legitimate content to overcome Bayesian solutions, which utilizes prior instances to determine the probability that a message is spam.
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