Spam filters have now become an integral part of Internet usage. Offering easy and user friendly methods of keeping unwanted mails away from the computer, these filters have become immensely popular amongst the users of World Wide Web.

Content-based filters are generally considered the best in terms of performance. Working on the simple principle of analyzing the message subject, headers and content and looking for indicators of spam, content-based spam filters block spam messages from entering the mailbox as soon as they encounter some suspicious words.

Some of the most commonly used spam filters are eXpurgate, Cloudmark, SpamPal, MailWasher Pro, Spamihilator, K9, Spam Bully, Spam Interceptor and many more.

Identifying and establishing a spam filter is not an easy task, as each spam filter has unique features. Moreover, this technology undergoes constant updates, and in such a dynamic scenario determining the best is not easy.

However, there are certain basic characteristics which a spam filter must have in order to function effectively. An ideal spam filter should be a combination of various filtering techniques, like content based, blacklisted/ whitelisted and volume-based filtration. It should not slow down the pace of the system. Also, no additional software or hardware support should be required, and it should be extremely user-friendly. Also, it should be flexible and adaptable to the filtering technique most suitable for the user, while requiring minimal maintenance

Spam filters certainly offer an extremely user-oriented and easy technique of blocking spam. However, apart from relying on technology, one may avoid unsolicited mails by practicing some common Internet safety tips. Apart from identifying private and professional mailing lists and operating them from separate mail accounts, one also needs to follow the professional ethics of using client-based email, as this is generally the worst hit by spam.

Every client-based email service provider, like Microsoft, issues certain guidelines for using the service. Adhering to these may bring down the number of spam mails incredibly. Following ethical Internet practices cautiously and using spam filters can offer a long-lasting and effective remedy to block spam messages.