Category: Managing Postfix Mail Server Linux Systems

This article describe how to set up and configure Postfix Mail Server with Dovecot and Squirrelmail On CentOS 6 at Local Area Network.

Set up and configure Postfix Mail Server to receive and send email on public area network (internet) with domain name ([email protected]) is very complex and difficult to set up, need much resources like static public ip address, stable server, etc.
As an alternative we can set up and configure Postfix to use Gmail as a Mail Relay, only need a Postfix Mail Server installed and a Gmail account  to configure MTA to relay outgoing mail through Gmail.

Postfix is a free open source mail transfer agent (MTA).

Dovecot is an open source IMAP and POP3 mail server for Unix/Linux systems.

SquirrelMail is a standards-based webmail package written in PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 (with no JavaScript required) for maximum compatibility across browsers.

It is important to disabled SELinux to reduce complexity in postfix configuration.
Remove default MTA sendmail first if it’s already installed

# yum remove sendmail

Add hostname entries in /etc/hosts file as shown below:

# vi /etc/hosts
127.0.0.1 localhost localhost.localdomain
::1 localhost localhost.localdomain
192.168.1.101 server.vpshelpdesk.local vpshelpdesk

Install Postfix package using the command:

# yum install postfix -y

Configuring Postfix, Edit /etc/postfix/main.cf,

# vi /etc/postfix/main.cf

find and edit the following lines:

## Line no 75 - Uncomment and set your mail server FQDN ##
myhostname = vpshelpdesk.local
## Line 83 - Uncomment and Set domain name ##
mydomain = vpshelpdesk
## Line 99 - Uncomment ##
myorigin = $mydomain
## Line 116 - Set ipv4 ##
inet_interfaces = all
## Line 119 - Change to all ##
inet_protocols = all
## Line 164 - Comment ##
#mydestination = $myhostname, localhost.$mydomain, localhost,
## Line 165 - Uncomment ##\
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
## Line 264 - Uncomment and add IP range ##
mynetworks = 192.168.1.0/24, 127.0.0.0/8
## Line 419 - Uncomment ##
home_mailbox = Maildir/

Save and exit the file. Start/restart Postfix service now:

# service postfix restart
# chkconfig postfix on

Testing Postfix mail server
First, create a test user called “SK“.

# useradd sk
# passwd sk

Access the server via Telnet and enter the commands manually shown in ## ##

# telnet localhost smtp
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 vpshelpdesk.local ESMTP Postfix
ehlo localhost ## type this command ##
250-server.vpshelpdesk.local
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<sk> ## Type this - mail sender address##
250 2.1.0 Ok
rcpt to:<sk> ## Type this - mail receiver address ##
250 2.1.5 Ok
data ## Type this to input email message ##
354 End data with <CR><LF>.<CR><LF>
welcome to vpshelpdesk mail server ## Enter the body of the email ##.
## type dot (.) to complete message ##
250 2.0.0 Ok: queued as B822221522
quit ## type this to quit from mail ##
221 2.0.0 Bye
Connection closed by foreign host.

Now navigate to the user “sk“ mail directory and check for the new mail:

# ls /home/sk/Maildir/new/
Sample output:

1390215275.Vfd00Ie04f8M357080.vpshelpdesk.local
A new mail is received to the user “sk“. To read the mail, enter the following command:
# cat /home/sk/Maildir/new/1390215275.Vfd00Ie04f8M357080.mail.local
Sample output:
Return-Path: <[email protected]>
X-Original-To: sk
Delivered-To: [email protected]
Received: from localhost (localhost [IPv6:::1])
by mail.local (Postfix) with ESMTP id B822221522
for <sk>; Mon, 20 Jan 2014 16:23:54 +0530 (IST)
Message-Id: <[email protected]>
Date: Mon, 20 Jan 2014 16:23:54 +0530 (IST)
From: [email protected]
To: undisclosed-recipients:;
welcome to vpshelpdesk mail server

Installing Dovecot
Dovecot is an open source IMAP and POP3 mail server for Unix/Linux systems. To install:

# yum install dovecot

Configuring Dovecot
Edit the file /etc/dovecot/dovecot.conf file,

#vi /etc/dovecot/dovecot.conf

Uncomment the following line:

## Line 20 - umcomment ##
protocols = imap pop3 lmtp

Edit file /etc/dovecot/conf.d/10-mail.conf file

#vi /etc/dovecot/conf.d/10-mail.conf

Make the changes as shown below:

## Line 24 - uncomment ##
mail_location = maildir:~/Maildir

Edit /etc/dovecot/conf.d/10-auth.conf

#vi /etc/dovecot/conf.d/10-auth.conf

And make the changes as shown below:

## line 9 - uncomment##
disable_plaintext_auth = yes
## Line 97 - Add a letter "login" ##
auth_mechanisms = plain login

Edit file /etc/dovecot/conf.d/10-master.conf,

# vi /etc/dovecot/conf.d/10-master.conf

Make changes as shown below:

## Line 83, 84 - Uncomment and add "postfix"
#mode = 0600
user = postfix
group = postfix

Start Dovecot service:

# service dovecot start
# chkconfig dovecot on

Testing Dovecot
It’s time to test Dovecot configuration. Enter the following command in Terminal:

#telnet localhost pop3
Enter the commands manually marked in red color:
Trying ::1...
Connected to localhost.
Escape character is '^]'.
+OK Dovecot ready.
user sk ## log in as user sk ##
+OK
pass centos ## input user password ##
+OK Logged in.
retr 1
+OK 439 octets
Return-Path: <[email protected]>
X-Original-To: sk
Delivered-To: [email protected]
Received: from localhost (localhost [IPv6:::1])
by server.vpshelpdesk.local (Postfix) with ESMTP id B822221522
for <sk>; Mon, 20 Jan 2014 16:23:54 +0530 (IST)
Message-Id: <[email protected]>
Date: Mon, 20 Jan 2014 16:23:54 +0530 (IST)
From: [email protected]
To: undisclosed-recipients:;
welcome to vpshelpdesk mail server
.
quit
+OK Logging out.
Connection closed by foreign host.

Good Dovecot is working!

Installing Squirrelmail
Make sure that you’ve installed and enabled EPEL repository. Now install Squirrelmail using the following command:

#yum install squirrelmail

Configuring Squirrelmail
Navigate to /usr/share/squirrelmail/config/ directory and run the command conf.pl:

# cd /usr/share/squirrelmail/config/
# ./conf.pl

The following wizard will open. Enter choice “1” to set your organization details:

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
The following wizard will open. Enter “1” again to modify your organization details:
SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Organization Preferences
1. Organization Name : SquirrelMail
2. Organization Logo : ../images/sm_logo.png
3. Org. Logo Width/Height : (308/111)
4. Organization Title : SquirrelMail $version
5. Signout Page :
6. Top Frame : _top
7. Provider link : http://squirrelmail.org/
8. Provider name : SquirrelMail
R Return to Main Menu
C Turn color off
S Save data
Q Quit
Command >> 1
Set your Organization name and press Enter:
SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Organization Preferences
1. Organization Name : vpshelpdesk
2. Organization Logo : ../images/sm_logo.png
3. Org. Logo Width/Height : (308/111)
4. Organization Title : SquirrelMail $version
5. Signout Page :
6. Top Frame : _top
7. Provider link : http://squirrelmail.org/
8. Provider name : vpshelpdesk Mail
R Return to Main Menu
C Turn color off
S Save data
Q Quit
Command >> s
Now enter “2” to setup mail Server settings such as domain name and mail agent etc.:

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 >> 2
Enter “1”, Enter your mail domain (ex. vpshelpdesk. local) and press Enter key.

SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Server Settings
General
-------
1. Domain : localhost
2. Invert Time : false
3. Sendmail or SMTP : Sendmail
A. Update IMAP Settings : localhost:143 (uw)
B. Change Sendmail Config : /usr/sbin/sendmail
R Return to Main Menu
C Turn color off
S Save data
Q Quit
Command >> 1
The domain name is the suffix at the end of all email addresses. If
for example, your email address is [email protected], then your domain
would be example.com.
[localhost]: unixmen.local
Enter “3” and change from sendmail to Postfix MTA (i.e. SMTP):

SquirrelMail Configuration : Read: config.php (1.4.0)
---------------------------------------------------------
Server Settings
General
-------
1. Domain : unixmen.local
2. Invert Time : false
3. Sendmail or SMTP : Sendmail
A. Update IMAP Settings : localhost:143 (uw)
B. Change Sendmail Config : /usr/sbin/sendmail
R Return to Main Menu
C Turn color off
S Save data
Q Quit
Command >> 3
Enter “2” to switch from sendmail MTA to postfix.

You now need to choose the method that you will use for sending
messages in SquirrelMail. You can either connect to an SMTP server
or use sendmail directly.
1. Sendmail
2. SMTP
Your choice [1/2] [1]: 2
Now enter “S” followed by “Q” to save and exit Squirrelmail configuration.

Create a squirrelmail vhost in apache config file:

#vi /etc/httpd/conf/httpd.conf

Add the following lines at the end:

Alias /webmail /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 Apache service:

#service httpd restart

Create users
Create some users for testing. In my case i create two users called “senthil“ and “kumar“ respectively.

# useradd senthil
# useradd kumar
# passwd senthil
# passwd kumar

Access Webmail
Now navigate to http://ip-address/webmail or http://domain-name/webmail from your browser. The following screen should appear. Enter the username and password of the user.

Now you’ll be able to access the user senthil mail box. Let us compose a test mail from user “senthil“ to user “kumar“. Click on the Compose link on the top. Enter the recipient mail id (ex. [email protected]), subject and body of the mail and click Send.

Now log out from user “senthil“ and log in to user “kumar“ mail and check for any new mail.

Hurrah! We have got a new mail from [email protected] mail id. To read the mail, click on it. You’ll now be able to read, reply, delete or compose a new mail.

That’s it for now. We’ve successfully configured a local mail server that will serve in/out mails within a local area network. But i want to configure a public mail server to send and receive mails to outside of our LAN, what should i do? That’s not that difficult either.

You should configure mail server with a public IP and request your ISP to put the MX record of your mail server into their DNS server and you’re done! Everything will be same as i described above.

Setup DNS server and add the Mail server MX records in the forward and reverse zone files. To install and configure DNS server, navigate to this link. And you’ll need to contact your ISP to point your external static IP to your mail domain.

This article taken from http://www.unixmen.com/install-postfix-mail-server-with-dovecot-and-squirrelmail-on-centos-6-4/