How to install Linux

How to install Ubuntu 10.04.

How to install SMTP, POP3, IMAP and Webmail service

Postfix will be providing the SMTP service, Dovecot will provide the POP3 and IMAP service, while Apache and SquirrelMail will provide the Webmail service.

1. How to install and setup Postfix SMTP server.

2. How to install and setup Dovecot POP3 and IMAP server.

3. Configure Postfix SMTP Authentication using Dovecot SASL.

4. How to install and setup SquirrelMail WebMail.

Before deploying your new mail server, see Mail Server Checklist to ensure your new mail server will have a good sending reputation and can be trusted.

How to create mailboxes and do miscellaneous tasks

This section will show you to do tasks like creating mailboxes, aliases, setting quota etc.

To create a mailbox, just create a new user account.

To avoid user account related problems, do not use uppercase letters when creating user names.

How to install MailScanner anti-virus and anti-spam filter.

You can greatly reduce the volume of spam and viruses reaching your mail server if you are willing to give up something. If you are willing to have your mail delayed (time), install Postgrey. If you are willing to spend (money), get the Barracuda Spam Firewall.

How to setup a mailing list or proxy address in Postfix.

Configuring MailScanner

1. Install MailScanner using the command below.

sudo apt-get install mailscanner

2. Edit the file /etc/MailScanner/virus.scanners.conf and change the path of clamav to /usr.

3. Edit the file /etc/MailScanner/MailScanner.conf and update the lines below.

%org-name% = your organization name
%org-long-name% = your full organization name
%web-site% = your mail support website or company website
Run As User = postfix
Run As Group = postfix
Incoming Queue Dir = /var/spool/postfix/hold
Outgoing Queue Dir = /var/spool/postfix/incoming
Incoming Work Group = clamav
Incoming Work Permissions = 0640
MTA = postfix
Virus Scanners = clamd
Use SpamAssassin = yes
SpamAssassin User State Dir = /var/spool/MailScanner/spamassassin

4. Edit the file /etc/default/mailScanner and update the line below

run_mailscanner=1

5. Edit the file /usr/sbin/mailscanner and add a -U parameter on the first line.

Integrating MailScanner into Postfix

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

header_checks = regexp:/etc/postfix/header_checks

2. Create the file /etc/postfix/header_checks and add the line below

/^Received:/ HOLD

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

3. Use the commands below to start MailScanner.

sudo service postfix restart
sudo service clamav-daemon start
sudo service mailscanner start

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

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

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.

The English language message templates used in MailScanner is stored in /etc/MailScanner/reports/en and can even be configured to add a disclaimer message to outgoing mails.

Installing SquirrelMail

1. Install squirrelmail using the command below.

sudo apt-get install squirrelmail

2. Add SquirrelMail into Apache using the commands below.

sudo cp /etc/squirrelmail/apache.conf /etc/apache2/sites-available/squirrelmail
sudo a2ensite squirrelmail
sudo service apache2 restart

3. If you encounter an error regarding apache being not able to determine the server’s fully qualified domain name, then use the command below to fix it.

echo ServerName $HOSTNAME | sudo tee /etc/apache2/conf.d/servername

4. Launch the SquirrelMail Configuration utility using the command below.

sudo squirrelmail-configure

5. Type in D and press Enter to select the Set pre-defined settings for specific IMAP servers menu. Type in dovecot and press Enter. Save your changes when you are done.

I recommend installing the Retrieve User Data plugin so the user’s name will appear whenever he or she sends an email in SquirrelMail.

6. Launch your browser and type in http://mail.acme.local/squirrelmail. Replace mail.acme.local with your own server name. Type in a valid username and password and click Login.

7. That’s it, it’s working.

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

Related Pages

How to customize the login page.

How to secure SquirrelMail using SSL.

How to add a password change utility.

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

Configure Dovecot

1. Edit the file /etc/dovecot/dovecot.conf using the command

sudo vi /etc/dovecot/dovecot.conf

and update the lines below

mail_location = maildir:~/Maildir
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh

2. Restart dovecot using the command

sudo service dovecot restart

Test Dovecot

Here’s a sample dovecot session. Replace johndoe and password with any valid user name and password.

johndoe@mail:~$ telnet localhost pop3
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
+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.
johndoe@mail:~$

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

Configure Postfix

1. Edit the file /etc/postfix/main.cf using the command

sudo vi /etc/postfix/main.cf

and add the line below

home_mailbox = Maildir/

In main.cf, lines starting with # are comments. Save the file after completing your changes.

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

If you are not familiar with vi, check out this quick vi tutorial.

2. Restart postfix using the command

sudo service postfix restart

Test Postfix

Here is a 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.

johndoe@mail:~$ telnet localhost smtp
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 mail ESMTP Postfix (Ubuntu)
ehlo localhost
250-mail
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<johndoe>
250 2.1.0 Ok
rcpt to:<johndoe>
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
test
.
250 2.0.0 Ok: queued as 9729067C17
quit
221 2.0.0 Bye
Connection closed by foreign host.
johndoe@mail:~$

johndoe@mail:~$ cd /home/johndoe/Maildir/new
johndoe@mail:~/Maildir/new$ ls
1185669817.Vfd00I18012M795756.mail
johndoe@mail:~/Maildir/new$ cat 1185669817.Vfd00I18012M795756.mail

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

johndoe@mail:~/Maildir/new$

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

How to install Linux

You can use either Red Hat Enterprise Linux 6 or CentOS 6. RHEL 6 can be purchased from Red Hat and comes with support. CentOS 5 on the other hand can be downloaded here.

1. How to install CentOS 6.

2. How to setup CentOS 6.

To edit configuration files, you can use vi editor or install the GUI based gedit using the command

yum install gedit

How to install SMTP, POP3, IMAP and Webmail service

Postfix will be providing the SMTP service, Dovecot will provide the POP3 and IMAP service, while Apache and SquirrelMail will provide the Webmail service.

1. How to install and setup Postfix SMTP server.

2. How to install and setup Dovecot POP3 and IMAP server.

3. Configure Postfix SMTP Authentication using Dovecot SASL.

4. How to install and setup SquirrelMail WebMail.

5. How to configure the firewall.

Before deploying your new mail server, see Mail Server Checklist to ensure your new mail server will have a good sending reputation and can be trusted.

How to create mailboxes and do miscellaneous tasks

This section will show you to do tasks like creating mailboxes, aliases, setting quota etc.

To create a mailbox, just create a new user account.

To avoid user account related problems, do not use uppercase letters when creating user names.

How to setup a mailing list or proxy address in Postfix.

How to configure Postfix to auto respond with vacation messages.

How to assign a mailbox quota in Postfix.

Install Webmin if you want a web-based interface to manage your mail accounts.

How to add antivirus and antispam filtering

We will be using Clam AntiVirus for virus scanning, SpamAssassin for the spam tagging and MailScanner to integrate them into Postfix.

1. How to install MailScanner.

2. How to install Clam AntiVirus (ClamAV).

3. MailScanner, ClamAV, SpamAssassin and Postfix Integration Guide.

You can greatly reduce the volume of spam and viruses reaching your mail server if you are willing to give up something. If you are willing to have your mail delayed (time), install Postgrey. If you are willing to spend (money), get the Barracuda Spam Firewall.

How to integrate Active Directory/LDAP

Integrating Active Directory/LDAP into your mail server will turn your Linux email server into a lean and mean Exchange like machine. And you won’t have to deal with Linux system accounts or edit configuration files for common tasks like creating mailboxes and mailing lists. And finally, you can provide your users with standard address book.

Active Directory/LDAP virtual users in Postfix and Dovecot.

How to use the Active Directory Distribution Group in Postfix.

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

Using Winbind to integrate Active Directory user accounts.
Another way to integrate Active Directory into your mail server. I highly recommend using the virtual user solution above instead of this one.

How to integrate MySQL or support multiple domains

To simplify administering multiple domains, the domains and mail accounts will be stored in MySQL and will be managed using Postfix Admin, a web based interface for handling domains, mailboxes and aliases.

How to install Postfix Admin.

MySQL virtual users in Postfix and Dovecot.

Install the SquirrelMail Postfix Admin Plugin if you want to enable the users to set their own vacation message, forwarding and password.

Configure Postfix and Dovecot

1. Edit the file /etc/dovecot/conf.d/10-master.conf and make sure your service auth section has the lines below.

service auth {	
  unix_listener /var/spool/postfix/private/auth {
	mode = 0666
	user = postfix
	group = postfix
  }	
}

2. Edit the file /etc/dovecot/conf.d/10-auth.conf and update the line below.

auth_mechanisms = plain login

3. Edit /etc/postfix/main.cf, find the keys below and change its values as follows or add it at the bottom of the file if the key (the word before the = sign) cannot be found.

mynetworks = 127.0.0.0/8
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions =  permit_mynetworks, 
    permit_sasl_authenticated, 
    reject_unauth_destination
broken_sasl_auth_clients = yes

4. Configure SELinux using the commands below. Here’s the content of postfixdovecotsasl.te

wget linuxmail.info/files/rhel6/postfixdovecotsasl.te
checkmodule -M -m -o postfixdovecotsasl.mod postfixdovecotsasl.te
semodule_package -o postfixdovecotsasl.pp -m postfixdovecotsasl.mod
semodule -i postfixdovecotsasl.pp

5. Restart the Dovecot and Postfix service. But if you installed MailScanner, restart MailScanner instead of Postfix. Learn how to restart services here.

Test Postfix

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

Sample postfix session

[root@mail ~]# telnet mail smtp

Replace mail with the name of your server. We should not use localhost since localhost is a trusted client ip address. And make sure the domain name you specified does not resolve to 127.0.0.1 which is the IP address of localhost.

Trying 192.168.0.1...
Connected to mail.acme.local (192.168.0.1).
Escape character is '^]'.
220 mail.acme.local ESMTP Postfix
ehlo localhost
250-mail.acme.local
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-AUTH LOGIN PLAIN
250-AUTH=LOGIN PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

Note the new 250-AUTH lines. See the old SMTP Telnet Test.

mail from:<johndoe>
250 2.1.0 Ok
rcpt to:<test@example.com>
554 5.7.1 <test@example.com>: Relay access denied

It works, now to check if we can send it after authenticating.

auth plain AGpvaG5kb2UAcGFzc3dvcmQ=
235 2.0.0 Authentication successful
rcpt to:<test@example.com>
250 2.1.5 Ok
quit
221 2.0.0 Bye
Connection closed by foreign host.
[root@mail ~]#

You can send to email addresses belonging to your domain without authentication. This is normal as it enables you to receive mail from the outside.

The gibberish text after AUTH PLAIN is the base64 encoded value of the user name johndoe and password password. You can generate your own base64 text using the form below.

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

Firewall Configuration (GUI)

This section describes how to use the Firewall Configuration tool to configure the firewall.

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

2. Click Close in the Firewall Configuration Startup window.

3. Type in the root password and click Authenticate.

If the Firewall Configuration Startup window does not disappear after clicking Close, click the window behind it to bring the Authenticate window into the foreground.

4. In the service list, check Mail (SMTP) and WWW (HTTP).

5. Click Other Ports and click Add.

6. Select 110 tcp pop3 and click Ok. Do the same for 143 tcp imap.

7. Finally, click Apply to save your changes.

Firewall Configuration (TUI)

This section describes how to use the Firewall Configuration text user interface (TUI) tool to configure the firewall.

1. Launch the Firewall Configuration tool using the command below.

system-config-firewall-tui

2. In Firewall Configuration screen, press the Customize button.

3. In the service list, check Mail (SMTP) and WWW (HTTP). Press Forward when you are done.

4. Press Add to add a custom port.

5. Type in 110 to the field Port and tcp to the field Protocol. Press OK when you are done. Do the same for 143:tcp.

6. After adding the two ports press Close.

7. Finally, press OK and press Yes to confirm overriding of firewall configuration.

You can see the list of service and port numbers using the command below.

getent services

Installing SquirrelMail

1. Install the EPEL repository package.

2. Install squirrelmail using the command below.

yum install squirrelmail

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

Configuring SquirrelMail

1. Launch the SquirrelMail Configuration utility using the command below.

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

If your Terminal window has a white background, make sure that the colors are off by looking for the command Turn color on. If the command is Turn color off, type in C and press Enter to turn the colors off. This will ensure that you will be able to read all of the text.

2. Type in D and press Enter to select the Set pre-defined settings for specific IMAP servers menu. Type in dovecot and press Enter.

3. Type in 2 and press Enter to select the Server Settings menu.

4. Type in 1 and press Enter to select the Domain menu. Type in your domain name and press Enter. Save your changes and quit when you are done.

5. Type the commands below to enable SquirrelMail to function properly under SELinux.

setsebool httpd_can_network_connect on
setsebool httpd_can_sendmail on

I recommend installing the Retrieve User Data plugin so the user’s name will appear whenever he or she sends an email in SquirrelMail.

Testing SquirrelMail

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

2. In the address box, type in http://localhost/webmail/src/configtest.php and press Enter. Check for any errors.

3. 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.

Relocating SquirrelMail into the domain root

By default, SquirrelMail is located in the /webmail of your domain. If you prefer to access SquirrelMail from the root of your domain, follow the steps below.

1. Create the file /etc/httpd/conf.d/sqroot.conf containing the lines below.

<VirtualHost *:80>
DocumentRoot /usr/share/squirrelmail
</VirtualHost>

If you are using SSL and you want to force users to use SSL, add the Redirect directive inside the VirtualHost section to redirect browsers to the secured version. See the example below.

redirect permanent / https://mail.acme.local

2. Restart the httpd service. Learn how to restart services here.

3. Now try browsing http://localhost

Related Pages

How to customize the login page.

How to secure SquirrelMail using SSL.

How to add a password change utility.

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