Linux Mail Server Setup and Howto Guide

If you weren’t able to succeed in integrating Active Directory into Linux, don’t worry. This page will show you how to test Kerberos authentication and join the Active Directory domain manually so you can identify the problem.

This page will show you how to join your Linux server into the Active Directory domain, how to integrate the Active Directory user accounts into the Linux user accounts and how to authenticate users in Active Directory using Winbind, a component of Samba.

A better way to integrate Active Directory into your Linux mail server is by using Postfix’s Virtual User Accounts.

Samba is installed by default when you select the Server installation type during the installation process. In case you need to install or reinstall it, just add the Windows File Server package located in the Servers category using the Package Manager tool.

Setup and Configure Winbind

1. Click System, select Administration and click Authentication. This will launch the Authentication Configuration window.

This page will guide you in configuring MailScanner, ClamAV and SpamAssassin to work in Postfix. Before proceeding, please make sure that all of the above components are already installed.

Here are the installation guides for the above components.

• How to install Postfix SMTP Server
• How to install Clam Anti-virus (ClamAV)
• How to install MailScanner

SpamAssassin is included in Red Hat Enterprise Linux 5 and CentOS 5 and it’s ready to go out of the box. Just add it using the Package Manager tool if you haven’t done so during installation.

Configuring MailScanner

1. Edit the file /etc/MailScanner/MailScanner.conf

Installing and setting up Postfix SMTP Server in Red Hat Enterprise Linux 5 or CentOS 5 is easy. Postfix has secure default settings so we just need to open it up a bit.

Install Postfix and Mail Transport Agent Switcher

1. If you did not add postfix and system-switch-mail-gnome during the CentOS installation, you can add it now using Package Manager tool.

MailScanner is an open source anti-virus and anti-spam filter for email servers. The anti-virus and anti-spam portion is delegated to third party applications. This article describes how to install MailScanner.

The installation requires some packages found in RPMforge so make sure it is available in your system. Learn how to add the RPMforge repository.

Getting MailScanner

1. Click the globe icon at the top near the System menu to launch the Firefox web browser.

 

If an error occurs, you probably did not install the Graphical Internet package. You can add it now using the Package Manager tool.

To install Clam AntiVirus (ClamAV), we are going to use the precompiled binaries from the RPMforge repository. Learn how to add the RPMforge repository.

Installing Clam AntiVirus

If you prefer not to use the GUI tool below, you can also install the Clam AntiVirus by typing in yum install clamd in a Terminal window.

1. Click Applications then click Add/Remove Software. This will launch the Package Manager window.

2. Click the Search tab. Next type in clamd and click the Search button.

3. Select the latest version of clamd then click Apply. Next click on Continue until it proceeds with the installation.

4. After installation, click Ok. You now have successfully installed Clam Antivirus.

5. Start the clamd service. Learn how to stop and start services here.

6. To test ClamAV AntiVirus, type in the command clamscan in a terminal window.

7. To update the virus database, type in the command freshclam in a terminal window.

Red Hat Enterprise Linux 5 and its derivative CentOS 5 includes a graphical tool called Security Level Configuration for configuring the firewall options. This guide describes how to use this tool to open up the ports necessary for providing an email server.

1. Click System, select Administration and click Security Level and Firewall. This will launch the Security Level Configuration window.

SquirrelMail is an open source standards-based webmail package written in PHP. When installed, SquirrelMail is ready out of the box. All it needs is an installed web server like Apache, SMTP server like Postfix, and IMAP server like Dovecot.

Here are the installation guides for Postfix and Dovecot.

• How to install Postfix SMTP Server
• How to install Dovecot POP3 and IMAP Server

Starting the Web Server

1. If you did not add Web Server and squirrelmail during installation, you can add it now. Using the Package Manager tool, add the Web Server package in the Servers category. Also add the optional package squirrelmail located in the Mail Server package under the category Servers.

Installing and setting up Dovecot in Red Hat Enterprise Linux 5 or CentOS 5 is easy. All we have to do is to enable the services we would like to provide and we are good to go.

Install Dovecot

1. If you did not add dovecot during the CentOS installation, you can add it now using Package Manager.

Enabling SMTP authentication in Postfix ensures that only users with valid accounts can send email outside your network (relaying). This prevents spammers from using your SMTP server as a spam broadcast station. Here’s how to do it in Postfix.