Book Image

SpamAssassin: A practical guide to integration and configuration

Book Image

SpamAssassin: A practical guide to integration and configuration

Overview of this book

As a busy administrator, you know Spam is a major distraction in todays network. The effects range from inappropriate content arriving in the mailboxes up to contact email addresses placed on a website being deluged with unsolicited mail, causing valid enquiries and sales leads to be lost and wasting employee time. The perception of the problem of spam is as big as the reality. In response to the growing problem of spam, a number of free and commercial applications and services have been developed to help network administrators and email users combat spam. Its up to you to choose and then get the most out of an antispam solution. Free to use, flexible, and effective, SpamAssassin has become the most popular open source antispam application. Its unique combination of power and flexibility make it the right choice. This book will now help you set up and optimize SpamAssassin for your network.
Table of Contents (24 chapters)
SpamAssassin
Credits
About the Author
About the Reviewers
Introduction
Glossary

The Auto-Whitelist


SpamAssassin manages an automatic whitelist (AWL). It actually functions as both an auto-blacklist and an auto-whitelist. Generally, an auto-blacklist is ineffective as spammers rarely use the same email address for any period of time. However, SpamAssassin tracks both the IP address of email sources and the email addresses used, adding to its effectiveness.

The auto-whitelist keeps a record of the SpamAssassin scores for emails from senders. Senders that only send ham emails receive a weighting towards ham by the auto-whitelist. If they later send an email marked as spam, then the SpamAssassin score for the new email will be adjusted downwards, due to their past behavior as a source of only ham emails. The converse is true of those who normally send spam.

The AWL works by adjusting the score of the email being processed towards the average of all previous emails received from that sender. The amount or strength of this adjustment can be altered using the auto_whitelist_factor...