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

Regular expressions


Procmail implements a form of regular expressions that operates slightly differently than other UNIX utilities. Here we cover the basic differences and guide the new user into the powerful world of regular expressions, their meanings, implementations, and uses.

We have already seen that Procmail matches are case insensitive unless the D flag is used. This is also true for regular expressions. Procmail also uses multiline matches by default.

Introduction to regular expressions

New users to the world of Linux and programming in general, may not be aware of the powerful features that regular expressions bring to processing data. In its simplest form, regular expressions can be understood as searching for a phrase or pattern anywhere in a body of data. The following simple example shows how we can match all mail items where the header and/or body contains the phrase mystical monsters and place the mail in a relevant folder.

:0 HB:
* mystical monsters
${MAILDIR}/monsters/

However...