install and configure postfix/dovecot centos 6

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.ostechnix.com

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.ostechnix.com ##line no 75 - uncomment and enter your host name
mydomain = ostechnix.com  ##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.ostechnix.com ESMTP Postfix
ehlo localhost
250-server.ostechnix.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:
250 2.1.0 Ok
rcpt to:
250 2.1.5 Ok
data
354 End data with .
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.ostechnix.com
[root@server new]# cat 1360236956.Vfd00I35afM181256.server.ostechnix.com Return-Path: 
X-Original-To: user1
Delivered-To: user1@ostechnix.com
Received: from localhost (localhost [IPv6:::1])
 by server.ostechnix.com (Postfix) with ESMTP id 117113FF18
 for ; Thu,  7 Feb 2013 17:05:32 +0530 (IST)
Message-Id: <20130207113547 .117113ff18="" server.ostechnix.com="">
Date: Thu,  7 Feb 2013 17:05:32 +0530 (IST)
From: user1@ostechnix.com
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: 
X-Original-To: user1
Delivered-To: user1@ostechnix.com
Received: from localhost (localhost [IPv6:::1])
 by server.ostechnix.com (Postfix) with ESMTP id 117113FF18
 for ; Thu,  7 Feb 2013 17:05:32 +0530 (IST)
Message-Id: <20130207113547 .117113ff18="" server.ostechnix.com="">
Date: Thu,  7 Feb 2013 17:05:32 +0530 (IST)
From: user1@ostechnix.com
To: undisclosed-recipients:;
test
.
quit 
+OK Logging out.
Connection closed by foreign host.
[root@server ~]#