Mail Server using Postfix, Dovecot and SquirrelMail in CentOS/RHEL/Scientific Linux 6.3 step by step guide

Before install postfix, remove sendmail from the server. Because sendmail is the default MTA in Redhat/CentOS.

[root@server ~]# yum remove sendmail

Prerequisites:

    The mail server should contain a valid MX record in the DNS server. Navigate to this link how to setup DNS server.
    Firewall and SELinux should be disabled.

[root@server ~]# service iptables stop
[root@server ~]# service ip6tables stop
[root@server ~]# chkconfig iptables off
[root@server ~]# chkconfig ip6tables off


[root@server ~]# vi /etc/selinux/config
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of these two values:
#     targeted - Targeted processes are protected,
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted


Reboot the server.
Scenario
In this tutorial my test box
Hostname     = server.arkit.co.in
IP Address    = 192.168.1.200/24
And my server is configured with proper MX record in DNS server.
Installation
Postfix is installed by default. If it is not installed, use the below command to install postfix.

[root@server ~]# yum install postfix

Configuration
Open the postfix config file /etc/postfix/main.cf. Find the below lines and edit them as shown below.

[root@server ~]# vi /etc/postfix/main.cf
myhostname = server.arkit.co.in ##line no 75 - uncomment and enter your host name
mydomain = arkit.co.in  ##line no 83 - uncomment and enter your domain name
myorigin = $mydomain  ##line no 99 - uncomment
inet_interfaces = all  ##line no 116 - change to all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain  ##line no 164 - add $domain at the end
mynetworks = 192.168.1.0/24, 127.0.0.0/8  ##line no 264 - uncomment and add your network range
home_mailbox = Maildir/  ##line no 419 - uncomment


Start the postfix service.

[root@server ~]# service postfix start
Starting postfix:                                          [  OK  ]
[root@server ~]# chkconfig postfix on


Test Postfix
The commands shown in bold letters should be entered by the user.


Note: The dot after the test command is important.

[root@server ~]# telnet localhost smtp
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 server.arkit.co.in ESMTP Postfix
ehlo localhost
250-server.arkit.co.in
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<user1>
250 2.1.0 Ok
rcpt to:<user1>
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
test
.
250 2.0.0 Ok: queued as 117113FF18
quit
221 2.0.0 Bye
Connection closed by foreign host.


Check Mail
Navigate to the user mail directory and check for the new mail.

[root@server ~]# cd /home/user1/Maildir/new/
[root@server new]# ls
1360236956.Vfd00I35afM181256.server.arkit.co.in
[root@server new]# cat 1360236956.Vfd00I35afM181256.server.arkit.co.in
Return-Path: <user1@arkit.co.in>
X-Original-To: user1
Delivered-To: user1@arkit.co.in
Received: from localhost (localhost [IPv6:::1])
 by server.arkit.co.in (Postfix) with ESMTP id 117113FF18
 for <user1>; Thu,  7 Feb 2013 17:05:32 +0530 (IST)
Message-Id: <20130207113547.117113FF18@server.arkit.co.in>
Date: Thu,  7 Feb 2013 17:05:32 +0530 (IST)
From: user1@arkit.co.in
To: undisclosed-recipients:;
test


Thats it. Postfix working now.
Install Dovecot

[root@server ~]# yum install dovecot

Configure Dovecot
Open the dovecot config file /etc/dovecot/dovecot.conf. Find and uncomment the line as shown below.

[root@server ~]# vi /etc/dovecot/dovecot.conf
protocols = imap pop3 lmtp

Open the file /etc/dovecot/conf.d/10-mail.conf and uncomment the line as shown below.

[root@server ~]# vi /etc/dovecot/conf.d/10-mail.conf
mail_location = maildir:~/Maildir  ##line no 24 - uncomment

Open the /etc/dovecot/conf.d/10-auth.conf and edit as shown below.

[root@server ~]# vi /etc/dovecot/conf.d/10-auth.conf
disable_plaintext_auth = no  ##line no 9 - uncomment and change from yes to no.
auth_mechanisms = plain login  ##line no 97 - add the text "login"

Open the /etc/dovecot/conf.d/10-master.conf and edit as shown below.

unix_listener auth-userdb {
    #mode = 0600
    user = postfix  ##line no 83 - uncomment and enter postfix
    group = postfix  ##line no 84 - uncomment and enter postfix


Start the dovecot service.

[root@server ~]# service dovecot start
Starting Dovecot Imap:                                     [  OK  ]
[root@server ~]# chkconfig dovecot on


Test Dovecot
The commands shown in bold should be entered by the user.

[root@server ~]# telnet localhost pop3
Trying ::1...
Connected to localhost.
Escape character is '^]'.
+OK Dovecot ready.
user user1
+OK
pass user1
+OK Logged in.
list
+OK 1 messages:
1 428
.
retr 1
+OK 428 octets
Return-Path: <user1@arkit.co.in>
X-Original-To: user1
Delivered-To: user1@arkit.co.in
Received: from localhost (localhost [IPv6:::1])
 by server.arkit.co.in (Postfix) with ESMTP id 117113FF18
 for <user1>; Thu,  7 Feb 2013 17:05:32 +0530 (IST)
Message-Id: <20130207113547.117113FF18@server.arkit.co.in>
Date: Thu,  7 Feb 2013 17:05:32 +0530 (IST)
From: user1@arkit.co.in
To: undisclosed-recipients:;
test
.
quit
+OK Logging out.
Connection closed by foreign host.
[root@server ~]#


Dovecot is working now.
Install Squirrelmail
Install EPEL repository first. And install SquirrelMail package from EPEL repository.

[root@server ~]# wget http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
[root@server ~]# rpm -ivh epel-release-6-8.noarch.rpm
[root@server ~]# yum install squirrelmail
[root@server ~]# service httpd start
Starting httpd:                                            [  OK  ]
[root@server ~]# chkconfig httpd on
[root@server ~]#



Configure Squirrelmail
Go to the squirrelmail config directory and use the command ./conf.pl to start configure as shown below.

[root@server ~]# cd /usr/share/squirrelmail/config/
[root@server config]# ./conf.pl

SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Main Menu --
1.  Organization Preferences
2.  Server Settings
3.  Folder Defaults
4.  General Options
5.  Themes
6.  Address Books
7.  Message of the Day (MOTD)
8.  Plugins
9.  Database
10. Languages
D.  Set pre-defined settings for specific IMAP servers
C   Turn color off
S   Save data
Q   Quit
Command >>1


Select option 1 and set organization details.

SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Organization Preferences
1.  Organization Name      : arkit
2.  Organization Logo      : ../images/sm_logo.png
3.  Org. Logo Width/Height : (308/111)
4.  Organization Title     : Welcome to arkit webmail
5.  Signout Page           :
6.  Top Frame              : _top
7.  Provider link          : http://arkit.co.in
8.  Provider name          : arkit
R   Return to Main Menu
C   Turn color off
S   Save data
Q   Quit
Command >>R


Press R to return main menu and select option 2. Enter your domain name and select dovecot in the Sendmail or SMTP parameter.

SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Server Settings General
-------
1.  Domain                 : arkit.co.in
2.  Invert Time            : false
3.  Sendmail or SMTP       : SMTP
A.  Update IMAP Settings   : localhost:143 (uw)
B.  Update SMTP Settings   : localhost:25
R   Return to Main Menu
C   Turn color off
S   Save data
Q   Quit
Command >> S


Once you done, press S to save datas and press Q to exit.
Add the following lines in the httpd.conf file at the end.

[root@server ~]# vi /etc/httpd/conf/httpd.conf
Alias /squirrelmail /usr/share/squirrelmail
<Directory /usr/share/squirrelmail>
    Options Indexes FollowSymLinks
    RewriteEngine On
    AllowOverride All
    DirectoryIndex index.php
    Order allow,deny
    Allow from all
</Directory>

Restart the httpd service.

[root@server ~]# service httpd restart
Stopping httpd:                                            [  OK  ]
Starting httpd:                                            [  OK  ]
[root@server ~]#


Create Users

[root@server ~]# useradd user1
[root@server ~]# useradd user2
[root@server ~]# passwd user1
[root@server ~]# passwd user2


Open the browser from any clients. Type the following in the address bar.

http://serveripaddress/webmail

or

http://yourdomainname/webmail