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Mail Filtering -- Apr 8 2010, 7:55 PM
whitelisting
A whitelist is a list of e-mail addresses or domain names from which an e-mail blocking program will allow messages to be received. E-mail blocking programs, also called a spam filters, are intended to prevent most unsolicited e-mail messages (spam) from appearing in subscriber inboxes. The list can be gradually compiled over a period of time, and can be edited whenever the user wants.
Bayesian filter - spam / ham
A Bayesian filter is a program that uses Bayesian logic , also called Bayesian analysis, to evaluate the header and content of an incoming e-mail message and determine the probability that it constitutes spam . Bayesian logic is an extension of the work of the 18th-century English mathematician Thomas Bayes.
Bayesian filters aren't perfect, but because spam characteristically contains certain types of text, such a program can be amazingly effective when it is fine-tuned over a period of time. A Bayesian filter works by categorizing e-mail into groups such as "trusted" and "suspect," based on a probability number (ranging from 0 or 0% to 1 or 100%). The categories are defined according to user preference.
Spammers are constantly trying to invent new ways to defeat spam filters. Certain words, commonly identified as characteristic of spam, can be altered by the insertion of symbols such as periods, or by the use of nonstandard but readable characters such as Â, Ç, Ë, or Í. But as the user instructs a Bayesian filter to quarantine or delete certain messages, the filter incorporates this data into its future actions. Thus a Bayesian filter improves with time, so it becomes more likely to block spam without also blocking desired messages.
Greylisting
A graylist (also spelled greylist) is a list of e-mail addresses or domain names a spam filter can use to identify suspected spam. If a message arrives from an address or domain on the list, it will be quarantined and then delivered to the subscriber only if the sender attempts to send the message again within a certain period of time. Once a sender has been recognized as legitimate, its address is removed from the list and future messages from that address can pass through the filter unhindered.
The chief advantage of graylisting is the fact that it eliminates most spam while giving desired e-mail traffic a chance to get through. It requires no special configuration efforts on the part of the end user and places no additional burden on the resources of the end user's computer. However, unless a sender transmits its first message to a graylist user twice from the same e-mail address within the prescribed time, the filter will reject the message.
A whitelist is a list of e-mail addresses or domain names from which an e-mail blocking program will allow messages to be received. E-mail blocking programs, also called a spam filters, are intended to prevent most unsolicited e-mail messages (spam) from appearing in subscriber inboxes. The list can be gradually compiled over a period of time, and can be edited whenever the user wants.
Bayesian filter - spam / ham
A Bayesian filter is a program that uses Bayesian logic , also called Bayesian analysis, to evaluate the header and content of an incoming e-mail message and determine the probability that it constitutes spam . Bayesian logic is an extension of the work of the 18th-century English mathematician Thomas Bayes.
Bayesian filters aren't perfect, but because spam characteristically contains certain types of text, such a program can be amazingly effective when it is fine-tuned over a period of time. A Bayesian filter works by categorizing e-mail into groups such as "trusted" and "suspect," based on a probability number (ranging from 0 or 0% to 1 or 100%). The categories are defined according to user preference.
Spammers are constantly trying to invent new ways to defeat spam filters. Certain words, commonly identified as characteristic of spam, can be altered by the insertion of symbols such as periods, or by the use of nonstandard but readable characters such as Â, Ç, Ë, or Í. But as the user instructs a Bayesian filter to quarantine or delete certain messages, the filter incorporates this data into its future actions. Thus a Bayesian filter improves with time, so it becomes more likely to block spam without also blocking desired messages.
Greylisting
A graylist (also spelled greylist) is a list of e-mail addresses or domain names a spam filter can use to identify suspected spam. If a message arrives from an address or domain on the list, it will be quarantined and then delivered to the subscriber only if the sender attempts to send the message again within a certain period of time. Once a sender has been recognized as legitimate, its address is removed from the list and future messages from that address can pass through the filter unhindered.
The chief advantage of graylisting is the fact that it eliminates most spam while giving desired e-mail traffic a chance to get through. It requires no special configuration efforts on the part of the end user and places no additional burden on the resources of the end user's computer. However, unless a sender transmits its first message to a graylist user twice from the same e-mail address within the prescribed time, the filter will reject the message.
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