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

Header Tests


Header tests focus on the message headers. The tests are mainly concerned with detecting fake headers and determining whether a message has been routed via an open relay.

For example, a header test could flag all emails that appear to have been sent over 72 hours ago, or sent at a future date. Most email servers have accurate clocks. However, spammers frequently use trojanned PCs, which may have inaccurate clocks, and so spam messages might have dates that are in the past or the future. Examining email headers is described in more detail later in the chapter.

Header tests do not form a large proportion of tests that SpamAssassin performs. These tests use up considerable amounts of CPU, memory, and disk I/O resources.