Book Image

Linux Email

Book Image

Linux Email

Overview of this book

Many businesses want to run their email servers on Linux for greater control and flexibility of corporate communications, but getting started can be complicated. The attractiveness of a free-to-use and robust email service running on Linux can be undermined by the apparent technical challenges involved. Some of the complexity arises from the fact that an email server consists of several components that must be installed and configured separately, then integrated together. This book gives you just what you need to know to set up and maintain an email server. Unlike other approaches that deal with one component at a time, this book delivers a step-by-step approach across all the server components, leaving you with a complete working email server for your small business network. Starting with a discussion on why you should even consider hosting your own email server, the book covers setting up the mail server. We then move on to look at providing web access, so that users can access their email out of the office. After this we look at the features you'll want to add to improve email productivity: virus protection, spam detection, and automatic email processing. Finally we look at an essential maintenance task: backups. Written by professional Linux administrators, the book is aimed at technically confident users and new and part-time system administrators. The emphasis is on simple, practical and reliable guidance. Based entirely on free, Open Source software, this book will show you how to set up and manage your email server easily.
Table of Contents (15 chapters)
Linux E-mail
Credits
About the Authors
About the Reviewers
Preface

Chapter 5. Securing Your Installation

Of all the things that can happen to your SMTP server, probably the worst is having it abused as an open relay—a server that relays mail to third parties without your permission. This will consume a lot of bandwidth (which can be costly), eat up server resources (possibly slowing down or stopping other services), and can be expensive in both time and money. A more serious consequence is that your e-mail server will probably end up on one or more blacklists, and any e-mail server that refers to those lists will refuse to accept any mail from your server until you have proven it to be relay safe. If you need to use e-mail in order to carry out business, you will have a big problem.

This chapter will explain how to:

  • Protect Postfix from relay abuse

  • Differentiate between statically and dynamically assigned IP addresses

  • Configure relay permissions using Postfix for static IP addresses

  • Use Cyrus SASL for authentication from unpredictable and dynamic IP addresses...