This document provides instructions for configuring a mail server on Red Hat/CentOS 6 that includes Postfix, Dovecot, SquirrelMail, and virus scanning/spam tagging. The 16 step process covers installing and configuring the software components, creating SSL certificates, enabling user authentication, and testing mail delivery to POP3/IMAP clients and via a web interface. Configuration files such as main.cf and dovecot.conf are edited to enable the required options.

1. MAIL SERVER
CONFIGURATION
(RHEL/CENTOS 6-6.X)
Chacheng Oo
Sr. System Engineer (IT)
DBL Group|BGMEA Complex( 12th Floor )| 23/1 Panthapath Link Road | Karwan Bazar | Dhaka-1215 |
Bangladesh| Tel:+88-02-8140207-12 |Fax: +88-02-8140214 | Cell: +88-01755647625 Or 01812-490773 |
Skype ID : Chacheng.oo |E-mail: chacheng@dbl-group.com , chacheng.oo@gmail.com | www.dbl-
group.com |

2. MAIL SERVER CONFIGURATION
 This article will show you how to setup an email server accessible using a
POP3, IMAP or web browser client. It will also show you how to include
virus scanning and spam tagging in the mail server.

3. Installing and configuring postfix
 Step 1:
Before installation assign a static ip and add a host entry for your domain to that IP in the
/etc/hosts file like below.
192.168.0.15 dblgroup.com mail
 Step 2:
Issue the below command to install postfix.
[root@mail ~]# yum -y install postfix

4. MAIL SERVER CONFIGURATION
 Step 3 :
Now issue the below command to install SMTP AUTH packages .
[root@mail ~]# yum -y install cyrus-sasl cyrus-sasl-devel cyrus-sasl-gssapi cyrus-sasl-md5 cyrus-sasl-plain
Postfix package installation is completed .
 Step 4 :
Issue the below commands one by one for creating SSL Cert.
[root@mail ~]# mkdir /etc/postfix/ssl
[root@mail ~]# cd /etc/postfix/ssl/
[root@mail ssl]# openssl genrsa -des3 -rand /etc/hosts -out smtpd.key 1024
[root@mail ssl]# chmod 600 smtpd.key
[root@mail ssl]# openssl req -new -key smtpd.key -out smtpd.csr

5. MAIL SERVER CONFIGURATION
[root@mail ssl]# openssl x509 -req -days 365 -in smtpd.csr -signkey smtpd.key –out smtpd.crt
[root@mail ssl]# openssl rsa -in smtpd.key -out smtpd.key.unencrypted
[root@mail ssl]# mv -f smtpd.key.unencrypted smtpd.key
[root@mail ssl]# openssl req -new -x509 -extensions v3_ca -keyout cakey.pem –out cacert.pem -days 365
Step 4 :
Now open /etc/postfix/main.cf file .
Find and comment the below lines .
#inet_interfaces = localhost #---> line no 116
#mydestination = $myhostname, localhost.$mydomain, localhost #--> line no 164

6. MAIL SERVER CONFIGURATION
and add these lines at the bottom of the file.
myhostname = mail.dblgroup.com
mydomain = dblgroup.com
myorigin = $mydomain
home_mailbox = mail/
mynetworks = 127.0.0.0/8
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
smtpd_sasl_auth_enable = yes
smtpd_sasl_type = cyrus
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtpd_tls_auth_only = no
smtp_use_tls = yes
smtpd_use_tls = yes

7. MAIL SERVER CONFIGURATION
smtp_tls_note_starttls_offer = yes
smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key
smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt
smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom

8. MAIL SERVER CONFIGURATION
Step 5 :
Now open /etc/postfix/master.cf file and add the below line after smtp
smtps inet n - n - - smtpd
-o smtpd_sasl_auth_enable=yes
-o smtpd_reject_unlisted_sender=yes
-o smtpd_recipient_restrictions=permit_sasl_authenticated,reject
-o broken_sasl_auth_clients=yes
Step 6 :
Now start postfix and saslauthd service
[root@mail ~]# service postfix start
[root@mail ~]# service saslauthd start

9. MAIL SERVER CONFIGURATION
 Issue the below commands to start the postfix and saslauthd at startup
[root@mail ~]# chkconfig --level 235 postfix on
[root@mail ~]# chkconfig --level 235 saslauthd on
Installing and configuring dovecot
Step 7 :
Issue this command to install dovecot
[root@mail ~]# yum -y install dovecot

10. MAIL SERVER CONFIGURATION
 Step 8 :
After installation open /etc/dovecot/dovecot.conf file and add the below line at the end of the file.
please make sure mail_location and home_mailbox in postfix configuration are using the same name.
protocols = imap pop3
mail_location = maildir:~/mail
pop3_uidl_format = %08Xu%08Xv
Step 9 :
Now start dovecot service
[root@mail ~]# service dovecot start
Issue the below command to start the dovecot at startup
[root@mail ~]# chkconfig --level 235 dovecot on

11. MAIL SERVER CONFIGURATION
Creating users and testing
 Step 10 :
Now create users to test your configuration.
[root@mail ~]# useradd -m chacheng -s /sbin/nologin
[root@mail ~]# useradd -m motin -s /sbin/nologin
and create passwords for the users created
[root@mail ~]# passwd chacheng
[root@mail ~]# passwd motin

12. MAIL SERVER CONFIGURATION
Installing and configuring squirrelmail
Step 11 :
you need to add EPEL repository to install squirrelmail package. you can find latest EPEL repository rpm
here ( http://ftp.jaist.ac.jp/pub/Linux/Fedora/epel/6/i386/repoview/epel-release.html )
[root@mail ~]# rpm –ivh http://ftp.jaist.ac.jp/pub/Linux/Fedora/epel/6/i386/epel-release-6-8.noarch.rpm
Step 12 :
Issue the below command to install squirrelmail.
[root@mail ~]# yum install squirrelmail
This command will install squirrelmail along with apache and php.

13. MAIL SERVER CONFIGURATION
 Step 13:
Now run the below command to configure squirrelmail .
[root@mail ~]# perl /usr/share/squirrelmail/config/conf.pl
»»» 1 »»» 1 »»» krizna (type Organization name ) »»» R ( return )
»»» 2 »»» 1 »»» ( hit space for empty Domain name ) and choose 3 »»» SMTP ( choose SMTP ) »»»
R ( return )
»»» D »»» dovecot ( type ) »»» press enter with default
»»» s ( save and quit)
 Step 14 :
Open /etc/httpd/conf.d/squirrelmail.conf file and uncomment below lines
# RewriteCond %{HTTPS} !=on
# RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

14. MAIL SERVER CONFIGURATION
 Step 15 :
start apache service
[root@mail ~]# service httpd start
Issue the below commands to start the httpd at startup
[root@mail ~]# chkconfig --level 235 httpd on
 Step 16 :
Now open http://serverip/webmail path in your browser . you could able to see the below page .
Login any problem or Error connecting to IMAP Server localhost
13. permission denied.
Then
[root@mail ~]# setsebool -P httpd_can_network_connect=1
[root@mail ~]# service httpd restart

15. MAIL SERVER CONFIGURATION
BACKUP FILE LOCATION:
1. cp /etc/hosts
2. cp /etc/postfix/main.cf
3. cp /etc/postfix/master.cf
4. cp /etc/dovecot/dovecot.conf
5. cp /etc/passwd