Postfix: The Definitive Guide: A Secure and Easy-to-Use MTA for UNIX

by Kyle D. Dent

Overview

Postfix is a Mail Transfer Agent (MTA): software that mail servers use to route email. Postfix is highly respected by experts for its secure design and tremendous reliability. And new users like it because it's so simple to configure. In fact, Postfix has been adopted as the default MTA on Mac OS X. It is also compatible with sendmail, so that existing scripts and programs continue to work seamlesslyafter it is installed.Postfix was written by well-known security expert Wietse Venema, who reviewed this book intensively during its entire development. Author Kyle Dent covers a wide range of Postfix tasks, from virtual hosting to controls for unsolicited commercial email.While basic configuration of Postfix is easy, every site has unique needs that call for a certain amount of study. This book, with careful background explanations and generous examples, eases readers from the basic configuration to the full power of Postfix. It discusses the Postfix interfaces to various tools that round out a fully scalable and highly secure email system. These tools include POP, IMAP, LDAP, MySQL, Simple Authentication and Security Layer (SASL), and Transport Layer Security (TLS, an upgrade of SSL). A reference section for Postfix configuration parameters and an installation guide are included.Topics include:

• Basic installation and configuration
• DNS configuration for email
• Working with POP/IMAP servers
• Hosting multiple domains (virtual hosting)
• Mailing lists
• Handling unsolicited email (spam blocking)
• Security through SASL and TLS

From compiling and installing Postfix to troubleshooting, Postfix: The Definitive Guide offers system administrators and anyone who deals with Postfix an all-in-one, comprehensive tutorial and reference to this MTA.

Product Details

ISBN-13:	9781449378790
Publisher:	O'Reilly Media, Incorporated
Publication date:	12/18/2003
Sold by:	Barnes & Noble
Format:	eBook
Pages:	280
File size:	3 MB

About the Author

Kyle D. Dent works as an independent consultant and software developer in the New York metropolitan area. He has designed and implemented various security, network, and web-based applications for technology and financial firms. He has been working with Postfix in various settings since it was released by IBM in 1998. Kyle grew up with computers in an IBM family, but originally started working in publishing and as a teacher of English as a Second Language. He is an avid supporter of public libraries serving as a trustee at his local library and on his regional library system board. He has recently started to learn the classical guitar.

Table of Contents

	Foreword	ix
	Preface	xi
1.	Introduction	1
	Postfix Origins and Philosophy	1
	Email and the Internet	3
	The Role of Postfix	5
	Postfix Security	6
	Additional Information and How to Obtain Postfix	8
2.	Prerequisites	10
	Unix Topics	10
	Email Topics	12
3.	Postfix Architecture	19
	Postfix Components	19
	How Messages Enter the Postfix System	20
	The Postfix Queue	22
	Mail Delivery	22
	Tracing a Message Through Postfix	25
4.	General Configuration and Administration	28
	Starting Postfix the First Time	29
	Configuration Files	30
	Important Configuration Considerations	41
	Administration	44
	master.cf	47
	Receiving Limits	51
	Rewriting Addresses	52
	chroot	56
	Documentation	57
5.	Queue Management	58
	How qmgr Works	58
	Queue Tools	62
6.	Email and DNS	68
	DNS Overview	68
	Email Routing	69
	Postfix and DNS	72
	Common Problems	75
7.	Local Delivery and POP/IMAP	77
	Postfix Delivery Transports	77
	Message Store Formats	78
	Local Delivery	80
	POP and IMAP	83
	Local Mail Transfer Protocol	84
8.	Hosting Multiple Domains	89
	Shared Domains with System Accounts	90
	Separate Domains with System Accounts	90
	Separate Domains with Virtual Accounts	91
	Separate Message Store	95
	Delivery to Commands	95
9.	Mail Relaying	103
	Backup MX	103
	Transport Maps	106
	Inbound Mail Gateway	109
	Outbound Mail Relay	110
	UUCP, Fax, and Other Deliveries	111
10.	Mailing Lists	112
	Simple Mailing Lists	113
	Mailing-List Managers	117
11.	Blocking Unsolicited Bulk Email	125
	The Nature of Spam	125
	The Problem of Spam	126
	Open Relays	127
	Spam Detection	127
	Anti-Spam Actions	129
	Postfix Configuration	130
	Client-Detection Rules	131
	Strict Syntax Parameters	143
	Content-Checking	144
	Customized Restriction Classes	147
	Postfix Anti-Spam Example	149
12.	SASL Authentication	151
	SASL Overview	152
	Postfix and SASL	154
	Configuring Postfix for SASL	154
	Testing Your Authentication Configuration	159
	SMTP Client Authentication	162
13.	Transport Layer Security	164
	Postfix and TLS	165
	TLS Certificates	165
14.	Content Filtering	174
	Command-Based Filtering	175
	Daemon-Based Filtering	177
	Other Considerations	181
15.	External Databases	183
	MySQL	184
	LDAP	190
A.	Configuration Parameters	195
B.	Postfix Commands	219
C.	Compiling and Installing Postfix	221
D.	Frequently Asked Questions	234
	Index	239

Editorial Reviews

Slashdot.org
This is an excellent book, Dent has explained the underlying methodology and use of Postfix well, taken the reader through all aspects of this MTA system and explained both the why and the how. I would recommend this book (and, as a result Postfix) to anyone looking for an MTA and a guide to configuring and running it.