Linux E-mail Set up, maintain, and secure a small office e-mail server Ian Haycox Alistair McDonald Magnus Bäck Ralf Hildebrandt Patrick Ben Koetter David Rusenko Carl Taylor BIRMINGHAM - MUMBAI This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 Linux E-mail Set up, maintain, and secure a small office e-mail server Copyright © 2009 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the authors, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: June 2005 Second edition: November 2009 Production Reference: 1051109 Published by Packt Publishing Ltd. 32 Lincoln Road Olton Birmingham, B27 6PA, UK. ISBN 978-1-847198-64-8 www.packtpub.com Cover Image by Vinayak Chittar ([email protected]) Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 Credits Authors Editorial Team Leader Ian Haycox Gagandeep Singh Alistair McDonald Project Team Leader Magnus Bäck Lata Basantani Ralf Hildebrandt Patrick Ben Koetter Project Coordinator Poorvi Nair David Rusenko Carl Taylor Proofreader Lesley Harrison Reviewers Patrick Chan Indexer Aric Pedersen Rekha Nair Acquisition Editor Graphics David Barnes Nilesh Mohite Development Editor Production Coordinator Ved Prakash Jha Aparna Bhagat Technical Editors Cover Work Gaurav Datar Aparna Bhagat Neha Patwari Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 About the Authors Ian Haycox is a freelance IT consultant based in France and actively contributes to open source projects. He has twenty-five years of software development experience in the enterprise integration, telecommunications, banking, and television sectors. Ian has a degree in Computer Science from the University of Hertfordshire, UK, and now runs his own web design company (http://www.ianhaycox.com/) and Linux programming consultancy. My thanks to Debbie for supplying me with copious amount of coffee and cheese sandwiches. Alistair McDonald is a software developer and IT consultant. He has worked as a freelancer in the UK for 15 years, developing cross-platform software systems in C, C++, Perl, Java, and SQL. He has been using open source software for over 20 years and implementing systems using it for the past 10 years. Last year, he gave up his freelance career and joined JDA Software, working in a technical role in their Service Industries division. Alistair is also the author of the book SpamAssassin: A practical guide to integration and configuration, published by Packt . I would like to thank my wife Louise for the support she has given me throughout the writing of all my books. Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 Magnus Bäck has been playing and working with computers since his childhood days. He is interested in everything in the computer field, from digital typography and compilers, to relational databases and UNIX. His interests also include e-mail services, and he is an active contributor to the Postfix mailing list. Besides computers, he enjoys photography, cars, and bicycling. Magnus holds a Master's degree in Computer Science and Engineering from Lund Institute of Technology, Sweden, and currently works with software configuration management for mobile phone software at Sony Ericsson Mobile Communications. Ralf Hildebrandt is an active and well-known figure in the Postfix community, working as a Systems Engineer for T-Systems, a German telecommunications company. He speaks about Postfix at industry conferences and hacker conventions, and contributes regularly to a number of open source mailing lists. Ralf Hildebrandt is the co-author of The Book of Postfix. Patrick Ben Koetter is an active and well-known figure in the Postfix community, working as an Information Architect. Patrick Koetter runs his own company, consulting and developing corporate communication for customers in Europe and Africa. He speaks about Postfix at industry conferences and hacker conventions, and contributes regularly to a number of open source mailing lists. Patrick Koetter is the co-author of The Book of Postfix. Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 David Rusenko was born in Paris, France, and spent most of his childhood overseas. He began working as a freelance Web Designer in 1996 and had his first experience with open source, a box copy of Red Hat 5.2, shortly after in 1999. After six years and as many versions of Red Hat, he now creates appealing web pages and devises solutions implementing high availability through clustering and alternate security models. He founded Aderes (http://www.aderes.net) in 2001, a company that provides e-mail and web-based security solutions. His search for an appropriate Webmail Platform for the company led him to SquirrelMail. Initially managing all aspects of the business—from the technical concerns to customer support—gave him the experience that he now contributes to the Webmail chapter of this book. David has studied both, Information Sciences and Technology (IST) and Management Information Systems (MIS) at the Pennsylvania State University. He speaks English and French fluently, and is conversational in Arabic. During his free time and vacations, he enjoys scuba diving, backpacking, playing racquetball, and playing electronic music records. Carl Taylor has worked over 20 years in the IT industry and has spent the majority of that time working on UNIX type systems, mainly communications or office automation projects. He was an early user of the UseNet network and taught himself to program in C through working on a variety of open source software. His experience covers roles including pre and post sales support, product development, end user training and management. Carl now runs his own web solutions development company "Adepteo", where they specialize in intranet and workflow products building on the best open source applications available. Whilst not working or looking after his children, Carl is something of a dance addict and is currently learning Latin Ballroom and Salsa. Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 About the Reviewers Patrick Chan is a programmer at Computer Bank, a not-for-profit organization that recycles and distributes donated computers to disadvantaged individuals and community groups. He has used Linux for quite a number of years, and has fond memories of starting off learning Linux as a newbie using the Gentoo distribution. His favorite tools include vim, GNU Screen, Z shell (zsh), Secure Shell (SSH), and Mutt. Aric Pedersen is the author of cPanel User Guide and Tutorial (ISBN 978-1-904811- 92-3) and Web Host Manager Administration Guide (ISBN 978-1-904811-50-3), both written for Packt Publishing. He also served as a reviewer for CUPS Administrative Guide (ISBN 978-1-84719-258-5), published by Packt Publishing. Aric has over 8 years of experience working as a System Administrator. He currently works for Hostdime.com, the world-class web host; and also for Netenberg.com, makers of Fantastico, the world's most popular web script installer for cPanel servers. I would like to thank Mike Kahn for all of his assistance over the past few years and also my good friend, Capt John "Jack" Grimes, Esq. USAF JAG Corps, who is the best friend a fellow could hope for, and his new wife, Kristin, who has shown incredible fortitude by marrying Jack (*smile*). I don't want to forget Francene Brown who is a good friend and a straight shooter (so rare to find these days). Finally, I'd like to thank my mother and Allen, because without them, nothing I've done would have been possible. Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 Download at WoweBook.Com This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009 111 Sutter Street, Suite 1800, San Francisco, , 94104 Table of Contents Preface 1 Chapter 1: Linux and E-mail Basics 5 Why manage your own e-mail server 6 What you need to host an e-mail server 7 Sizing the hardware of your e-mail server 8 Main