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 select the Windows File Server package in the Package Management tool.

Setup and Configure Winbind

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

2. Check the Enable Winbind Support and click Configure Winbind. This will launch the Winbind Settings window.

3. In the Winbind Settings window, set the Security Model to ads and fill in the Winbind Domain, Winbind ADS Realm and Winbind Domain Controllers. See sample settings below.

 

Winbind Domain

acme

Winbind ADS Realm

acme.local

Domain Controllers

server1.acme.local,server2.acme.local

To ensure the success of the Active Directory integration, make sure that you can ping the domain controllers and that the difference between the domain controllers’ clock and the mail server’s clock is not more than five minutes.

4. Click Join Winbind Domain. You will be asked to save your changes, click Save. In the Joining Winbind Domain window, fill in the Domain Administrator and Password. Click Ok when you are done. Click Ok again to close the Winbind Settings window.

5. Click the Authentication tab and check the Enable Winbind Support and Local authorization is sufficient for local users. Click Ok when you are done.

6. Open the file /etc/samba/smb.conf for editing and change winbind use default domain to yes.

winbind use default domain = yes

7. Create the folder that will contain the home directory of the Active Directory users. From the terminal window, type in the commands below.

mkdir /home/DOMAIN
chmod 777 /home/DOMAIN

Replace DOMAIN with your domain. Make sure to capitalize your domain like ACME in our example.

We changed the directory permission to 777, meaning anyone can read, write and execute because the users’ home directory will be created later by Postfix or Dovecot when a mail is received or a user checks his email. The created home directory on the other hand will have its permission set to read, write and execute by the owner only.

8. Restart the winbind service. Learn how to restart services here.

Test the Active Directory Integration

1. From a terminal window, type in wbinfo -u. You should see the Active Directory user accounts.

2. Try the Active Directory authentication, type in wbinfo -a "username"%"password".

3. Finally, type in getent passwd. You should see the Linux system accounts along with the Active Directory user accounts.

If it doesn’t work, visit the Active Directory Troubleshooting page.

Reconfiguring Postfix and Dovecot to Create the Home Directory

To store the mails, Postfix and Dovecot needs to create the username/Maildir directory. Postfix can create the Maildir directory and all the necessary parent directories. Unfortunately, Dovecot can only create the mail directory which in this case is Maildir and will fail if the parent directory username does not exist. Thus, we need to reconfigure Postfix and Dovecot to skip the Maildir directory and store the mails directly into the username directory which is the user’s home directory.

1. Edit the file /etc/postfix/main.cf and change the line below.

home_mailbox = /

2. Edit the file /etc/dovecot.conf and change the line below.

default_mail_env = maildir:~/

3. Restart Postfix or MailScanner (depends if you installed MailScanner) and Dovecot. Learn how to restart services here.

That’s it. The home directory should be now automatically created by Postfix and Dovecot whenever you receive or retrieve mails.

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

2. For a mail server with webmail, check WWW (HTTP) and Mail (SMTP) in the Trusted services list. There are only four predefined trusted services, the other services will have to be entered into the Other ports field.

3. We also need to open the ports for the POP3 and IMAP services. In the Other ports field, type in 110:tcp,995:tcp,143:tcp,993:tcp. The service and its corresponding port number is provided below.

 

Service

Port

HTTPS

443:tcp

POP3

110:tcp

POP3S

995:tcp

IMAP

143:tcp

IMAPS

993:tcp

 

Port 443:tcp is automatically added if you check the WWW (HTTP) service.

You can see more service and port numbers by typing in getent services from the Terminal window.

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 CentOS 4 and ready to go out of the box. Just add it using the Package Management tool if you haven’t done so during CentOS installation. SpamAssassin is located in the Mail Server package.

Configuring MailScanner

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

%org-name% = your organization name
%org-long-name% = your full organization name
Run As User = postfix
Run As Group = postfix
Incoming Queue Dir = /var/spool/postfix/hold
Outgoing Queue Dir = /var/spool/postfix/incoming
MTA = postfix
Virus Scanners = clamd
Clamd Socket = /tmp/clamd.socket
Use SpamAssassin = yes
SpamAssassin User State Dir = /var/spool/MailScanner/spamassassin

2. Click Applications and click File Browser to launch the File Browser window and go to the /var/spool/MailScanner directory.

3. In the File Browser window, click File and click Create Folder. Name the new folder spamassassin.

4. Right click on the folder incoming and click Properties.

5. In the Properties window, click the Permissions tab. In the Permissions page, set the File owner as postfix, the File group as postfix and check only the Owner Read, Write and Execute. Click Close when you are done. Repeat this for the quarantine and spamassassin folders.

Integrating MailScanner into Postfix

1. Edit the file /etc/postfix/main.cf and remove the # in front of the line below

header_checks = regexp:/etc/postfix/header_checks

2. Edit the file /etc/postfix/header_checks and add the line below to the bottom of the file

/^Received:/ HOLD

This will now place all incoming mail into the holding area until released by MailScanner.

3. MailScanner should now be the one to start the Postfix service. Stop the Postfix service and start the MailScanner service in that order. Learn how to stop and start services here.

4. Test if Postfix is still working. See Test Postfix using Telnet.

Congratulations

Congratulations, your mails are now checked for spam and viruses. Each mail you send or receive will now contain the lines below to indicate that MailScanner is doing its job.

This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

Getting MailScanner

1. Click the globe icon at the top near the Actions 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 Management tool.

2. In the address box, type in http://www.mailscanner.info/downloads.html and press Enter. Download the stable version for RedHat, Fedora and Mandrake Linux.

Building and Installing MailScanner

1. The MailScanner source code should now be on your desktop. Right click the newly downloaded file and click Extract Here.

2. After extracting, a MailScanner folder should be found on your Desktop. Double click the MailScanner folder to open it.

3. Next, double click the file install.sh. On the Run or Display window, select Run in Terminal. This will now build and install MailScanner. This will take a while so just wait until the Terminal window disappears.

Adding Dag Wieers RPM Repository to Yum

1. Click Applications, select System Tools and click Terminal. This will launch the Terminal window. Type in the command cd /etc/yum.repos.d and press Enter. This will bring us to the Yum repository configuration directory.

2. From this directory download the Yum repository configuration file by typing in the command
wget http://www.linux-mail.info/files/dag-clamav.repo and press Enter. This is what the file dag-clamav.repo looks like.

Installing Clam AntiVirus

3. To install ClamAV AntiVirus, type in the command
yum install clamav clamav-devel clamd and press Enter. When asked to confirm download, type in y and press Enter.

Using Clam AntiVirus

4. To use ClamAV AntiVirus, type in the command clamscan and press Enter.

5. To update the virus database, type in the command freshclam and press Enter.

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 the CentOS installation, you can add it now. Using the Package Management tool, add the Web Server package. Also add squirrelmail located inside the Mail Server package.

2. Start the httpd service. Learn how to start and stop services here.

Testing SquirrelMail

1. Click the globe icon at the top near the Actions 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 Management tool.

2. In the address box, type in http://localhost/webmail and press Enter. Type in a valid username and password and click Login.

3. That’s it, it’s working.

If you encounter any problems, check the log file at /var/log/maillog.

Related Pages

How to add a password change utility.

How to add Active Directory/LDAP into the SquirrelMail Addressbook.

How to automatically update the user’s personal information.

Install Dovecot

1. If you did not add dovecot during the CentOS installation, you can add it now. Dovecot is located in the package Mail Server. Learn how to add or remove applications here.

Configure Dovecot

1. Click Applications then click File Browser. This will launch the File Browser window.

2. In the Location field, type in /etc and press Enter.

3. Double click on the file dovecot.conf to open it for editing. We need to change a few key items.

protocols = pop3 pop3s imap imaps
default_mail_env = maildir:~/Maildir/
client_workarounds = oe6-fetch-no-newmail outlook-idle outlook-pop3-no-nuls

4. Start the dovecot service. Learn how to start and stop services here.

Test Dovecot

1. Click Applications, select System Tools, and click Terminal. This will launch the Terminal window.

2. In the Terminal window, type in the highlighted commands below.

Sample dovecot session. Replace johndoe and password with any valid user name and password.

[root@mail ~]# telnet localhost pop3
+OK dovecot ready.
user johndoe
+OK
pass password
+OK Logged in.
list
+OK 1 messages:
1 622
.
retr 1
+OK 622 octets
Return-Path: <johndoe@mail.acme.local>
X-Original-To: johndoe
Delivered-To: johndoe@mail.acme.local
Received: from localhost.localdomain (localhost.localdomain [127.0.0.1])
        by mail.acme.local (Postfix) with SMTP id 9729067C17
        for <johndoe>; Thu, 22 Feb 2007 09:06:37 -0500 (EST)
Message-Id: <20070222140640.9729067C17@mail.acme.local>
Date: Thu, 22 Feb 2007 09:06:37 -0500 (EST)
From: johndoe@mail.acme.local
To: undisclosed-recipients:;
X-IMAPbase: 1172153557 1
Status: O
X-UID: 1
Content-Length: 5
X-Keywords:


test
.
quit
+OK Logging out.
Connection closed by foreign host.
[root@mail ~]#

If you encounter any problems, check the log file at /var/log/maillog.

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. Postfix is located in the package Mail Server while system-switch-mail-gnome is in X Windows System. Learn how to add or remove applications here.

Switch to Postfix from Sendmail

By default, Sendmail is the active SMTP server. Here’s how to change it.

1. Click Applications, select Preferences, select More Preferences and click Mail Transport Agent Switcher. This will launch the system-switch-mail window.

2. In the system-switch-mail window, select Postfix and click Ok.

Configure Postfix

1. Click Applications then click File Browser. This will launch the File Browser window.

2. In the Location field, type in /etc/postfix and press Enter.

3. Double click on the file main.cf to open it for editing. We need to make it listen to network request, accept mails bound to our domain and use maildir which is a better mailbox format than mbox the default.

inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
home_mailbox = Maildir/

Make sure that all mail_spool_directory lines are commented out. Otherwise, it will override the setting in the home_mailbox line above.

4. Restart the postfix service. Learn how to restart services here.

Test Postfix

1. Click Applications, select System Tools, and click Terminal. This will launch the Terminal window.

2. In the Terminal window, type in the highlighted commands below.

Sample postfix session. Replace johndoe with any valid user account. The dot after the line test is a command that should be typed in.

If you need to add new user accounts, learn how to add or remove user accounts here.

[root@mail ~]# telnet localhost smtp
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
220 mail.acme.local ESMTP Postfix
ehlo host
250-mail.acme.local
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250 8BITMIME
mail from: johndoe
250 Ok
rcpt to: johndoe
250 Ok
data
354 End data with <CR><LF>.<CR><LF>
test
.
250 Ok: queued as 9729067C17
quit
221 Bye
Connection closed by foreign host.
[root@mail ~]#

[root@mail ~]# cd /home/johndoe/Maildir/new
[root@mail new]# ls
1185669817.Vfd00I18012M795756.mail.acme.local
[root@mail new]# cat 1185669817.Vfd00I18012M795756.mail.acme.local

From johndoe@mail.acme.local  Thu Feb 22 21:48:28 2007
Return-Path: <johndoe@mail.acme.local>
X-Original-To: johndoe
Delivered-To: johndoe@mail.acme.local
Received: from localhost.localdomain (localhost.localdomain [127.0.0.1])
        by mail.acme.local (Postfix) with SMTP id 9729067C17
        for <johndoe>; Thu, 22 Feb 2007 21:48:26 -0500 (EST)
Message-Id: <20070222134827.9729067C17@mail.acme.local>
Date: Thu, 22 Feb 2007 21:48:26 -0500 (EST)
From: johndoe@mail.acme.local
To: undisclosed-recipients:;

test

[root@mail mail]#

If you encounter any problems, check the log file at /var/log/maillog.

Review your Postfix aliases configuration file. There are some predefined email aliases that might conflict with your existing mail accounts like sales, marketing, info, etc.

By default Postfix does not require authentication to send emails. This means any Tom, Dick and Harry that have access to your network can use your SMTP server to send spam emails. Learn how to enable SMTP Authentication (SMTP AUTH) in Postfix here.