How do Spam Filters Work?

People who work with email on a daily basis often find that using a spam filter to quickly sort through irrelevant messages is a smart move. It’s important to have a basic understanding of how these filters work, however. Those who don't set them up properly may find themselves either flooded with junk or constantly searching for misplaced messages.

Language spam filters are an easy type of filter to use, since they merely discard all emails not written in the recipient's native language. The Internet is a global marketplace, so spammers come from around the world. With this type of filter, however, users don’t have to be bothered by annoying sales pitches in a languages they can’t read.

Content filters use sophisticated programming rules to determine whether or not an email is likely to be spam based on the text of the message and other relevant characteristics. This approach is quite effective at minimizing spam, but it does occasionally result in the misdirection of requested email newsletters and other similar bulk messages. People who use this type of filter will want to check their spam folder on a regular basis to make sure no errors have been made.

Header spam filters are similar to content filters, but they attempt to see if the header information on an email message appears to have been forged. Although email with a forged header is almost certainly spam, not all spam messages have forged headers. Therefore, this filter is best used in conjunction with other email management tools.

User spam filters can be effective, but they require a significant time investment to use properly. People who use them will need to make a point of examining all spam emails they receive and set up a series of rules for the email client to use in order to filter all incoming messages. For example, an individual could have all emails from her friends and work associates delivered to one inbox, all email newsletters she's requested sent to a second box, and all other messages delivered to third box.

Those who find themselves completely overwhelmed with the amount of spam they receive on a daily basis may find that permission spam filters may be the solution they've been searching for. This type of filter blocks all email that does not come from an approved source. When a person uses this type of filter and someone sends her a message for the first time, the sender will receive an automatic reply requesting that he complete a validation form. If the sender fails to complete this form, the message is blocked. The form must only be filled out one time, but computer users should be aware that many people find this extra step to be a nuisance in their correspondence.