Spam or unsolicited commercial email has become a real epidemic that, as well as slowing down users' communications, also has a significant financial impact in corporate environments.
According to Spam Filter Software Review, in 2002, in the United States alone, junk mail cost businesses almost 9 billion dollars. What's more, in 2003, 40 percent of the emails circulating around the Internet were spam and each user received an average of 2,200 spam messages a year.
Apart from that, spam can also cause corporate networks to slow down and increase bandwidth consumption, resulting in a dramatic increase in these figures. Therefore, it is obvious that spam protection, especially in corporate networks, must be given priority.
Spam can also be used as a means of spreading an even more dangerous threat: computer viruses. A spam message could easily include an attachment carrying a virus or a link to an apparently interesting website, from which malicious code can be downloaded without the user realizing. In the most extreme scenario, a virus could even be hiding in the message code.
None of these tactics are new; they have already been used to infect computers. However, just because they are known, it does not make them any less dangerous. In networks with a large number of users, it is not difficult for one of those users to download or run a virus hidden in a spam message, which will then spread across the network.
A basic measure to adopt to prevent spam from getting into users' mailboxes is to filter email messages. There are a large number of applications that allow network administrators to define rules that will help identify junk emails. They can configure them to filter email messages by subject, key word, domain, IP address of the sender of the message, etc.
However, spam is evolving at the same pace as security systems, and this means that just filtering messages is not enough. Spammers use all kinds of ruses to slip past any obstacles that try to stop them from reaching their target and for this reason, the system used must also intelligently analyze each message, as well as having the capacity to "learn". This means that it must be able to identify spam messages with minimum administrator intervention.
In companies, correctly identifying spam is not the only problem, but also managing the huge amount of spam messages received every day. Therefore, anti-spam tools must solve this problem. A good solution is to use a computer dedicated to blocking and deleting spam, installed at the connection between the corporate network and the Internet.