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

Examining Headers


Email headers have a specific format. They take the form of a series of records. Each record starts on a new line, with a word followed by a colon. The word can be hyphenated, so Return-Path: in the following example indicates the start of an email header.

Email headers can span several lines. If a line starts with a space or a tab character, it is a continuation of the previous header.

The following example shows the headers concerned with overall delivery details—who any bounce messages should be sent to, who the email was destined for, and who it was finally delivered to.

Return-Path: <[email protected]>
X-Original-To: [email protected]
Delivered-To: [email protected]

The following lines show the MTAs that the email was routed through on its way from sender to recipient. Each MTA adds a line above the other lines as it processes the email.

Received: from unknown (HELO 81.21.65.156) (218.14.129.227)
by server25.lb.an-isp.co.uk with SMTP; 29 Jun 2004 04:27:31...