How to setup mail server using Postfix, Dovecot and SquirrelMail in CentOS/RHEL
In this tutorial, we explains How to setup mail server using Postfix, Dovecot and SquirrelMail in CentOS/RHEL
Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail.
Dovecot is an open-source IMAP and POP3 server for Linux/UNIX-like systems.
SquirrelMail is a project that provides both a web-based email client and a proxy server for the IMAP protocol.
Prerequestics:
Step 1. Set your server hostname
To set your server hostname, edit /etc/sysconfig/network file
[root@mail ~]# vim /etc/sysconfig/network
Step 2. Assign ststic IP and assign host entry in /etc/hosts
[root@mail ~]# vim /etc/hosts
Step 3. Restart Network Service
[root@mail ~]# /etc/init.d/network restart
Step 4. Reboot your system
Step 5. Check your hoatname by following command
[root@mail ~]# hostname
Step 6. Disable your firewall and selinux
[root@mail ~] # service iptables stop
[root@mail ~] # service ip6tables stop
[root@mail ~]# chkconfig iptables off
[root@mail ~]# chkconfig ip6tables off
To disable selinux open /etc/selinux/config file and change SELINUX=disabled
[root@mail ~]# vim /etc/selinux/config
Installation Steps
Install Postfix
[root@mail ~]# yum remove sendmail
Step 2. Install Postfix
[root@mail ~]# yum install postfix
Step 3. Install SMTP AUTH Packages
[root@mail ~]# yum -y install cyrus-sasl cyrus-sasl-devel cyrus-sasl-gssapi cyrus-sasl-md5 cyrus-sasl-plain
Step 4. Create SSL Certificate
[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
[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 5. Open /etc/postfix/main.cf file
Find and comment below lines
inet_interfaces = localhost --->line no.116
mydestination = $myhostname, localhost.$mydomain, localhost ----->line no.164
Add these lines at the end of file
myhostname = mail.server.com
mydomain = server.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
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
Step 6. Open /etc/postfix/master.cf and add lines 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 7. Start postfix and saslauthd service
[root@mail ssl]# service postfix start
[root@mail ssl]# service saslauthd start
Step 8. Add service on startup
[root@mail ~]# chkconfig postfix on
[root@mail ~]# chkconfig saslauthd on
Step 9. check smtp connectivity.
[root@mail ~]# telnet localhost smtp and type 'ehlo localhost'
Install Dovecot
Step 1. Install and Configure dovecot.
[root@mail ~]# yum install dovecot
Step 2. After install open /etc/dovecot/dovecot.conf and add the below lines at the end of file.
[root@mail ~]# vim /etc/dovecot/dovecot.conf
protocols = imap pop3
mail_location = maildir:~/mail
pop3_uidl_format = %08Xu%08Xv
Step 3. Start dovecot service
[root@mail ~]# service dovecot start
Step 4. Add dovecot service on startup
[root@mail ~]# chkconfig dovecot on
Step 5. Test pop3 connectivity
[root@mail ~]# telnet localhost 110 (pop3)
Step 6. Create a user and test
[root@mail ~]# useradd -m mortred -s /sbin/nologin
[root@mail ~]# useradd -m pugna -s /sbin/nologin
[root@mail ~]# passwd mortred
[root@mail ~]# passwd pugna
Install Squirrel mail
Step 1. Download Squirrel Mail
# wget http://downloads.sourceforge.net/project/squirrelmail/stable/1.4.22/squirrelmail-webmail-1.4.22.zip
Step 2. Unzip Packages to /var/www/html/ directory
# unzip squirrelmail-webmail-1.4.22.zip -d /var/www/html/
Step 3. Rename squirrelmail-webmail-1.4.22 to webmail
# mv /var/www/html/squirrelmail-webmail-1.4.22/ /var/www/html/webmail
Step 4. Change owner
# chown -R apache: /var/www/html/webmail/
Step 5. # cd /var/www/html/webmail/config
Step 6. Rename config_default.php to config.php
# cp -p config_default.php config.php
Step 7. start apache service
[root@mail ~]# service httpd start
Step 8. Add apache service on startup
[root@mail ~]# chkconfig httpd on
Step 9. Run the below command to configure squirrelmail
[root@mail ~]# perl /var/www/html/webmail/config/conf.pl
Step 10. Open config.php and edit as following
[root@mail ~]# vim config.php
$domain = 'YOURDOMAIN.COM';
$data_dir = '/var/www/html/webmail/data/';
$attachment_dir = '/var/www/html/webmail/attach/';
$smtpServerAddress = 'localhost';
$imapServerAddress = 'localhost';
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Note: Increase SquirrelMail maximum attachment size.
[root@mail ~]#vim /etc/php.ini
Search for upload_max_filesize.
Change 2M to something else, for example 5M.
If the upload_max_filesize is larger than post_max_size, you must increase post_max_size so that it's bigger than upload_max_size
If the value of post_max_size is larger than memory_limit, you must increase memory_limit so that it's larger than post_max_size.
Save your changes to the file.
Restart your web server.
If uploading the file is slow, you may have to increase the max_execution_time so that the script does not terminate before the entire file is uploaded.
Testing
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