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

Configuring Postfix network maps


When the Internet was mainly used by academics, no one had to protect their mail servers from relay abuse. In fact, not many people had a mail server, and so permitting others who did not have an e-mail server to relay e-mail using your server was considered a service to them.

This changed with the advent of people who soon became known as spammers. They would abuse open relays to send advertisements to large numbers of remote recipients leaving the owner of the mail server to pay for the traffic.

This is when postmasters started to handle relay permissions restrictively. They used to permit relaying only for trusted IP addresses, refusing messages from other IP addresses. A trusted IP address in this context was an IP address that could be associated statically (refer the Static IP Ranges section) with a host that belonged to a known user, or a range of IP addresses known to belong to a trusted network. It worked well as most computers would have static IP...