Install Postfix MTA (Mail Transfer Agent)
Use the following command to install postfix in debian
#aptitude install postfix postfix-tls libsasl2 sasl2-bin libsasl2-modules popa3d
During installation, postfix will ask for few questions like name of server and answer those questions by entering your domain name and select Internet site for postfix.
Postfix configuration file is located at:/etc/postfix/main.cf. You can edit this file using popular text editor vi /etc/postfix/main.cf
Restart Postfix Server using the following command
#/etc/init.d/postfix restart
Install Dovecot
Dovecot is POP3/IMAP server which needs MTA like Postfix to work properly.
#aptitude install dovecot-imapd dovecot-pop3d dovecot-common
Dovecot configuration file is located at: /etc/dovecot/dovecot.conf
Before we proceed we need to make some changes with dovecot configuration file. Double check the following entries in the file if the values are entered properly.
Edit the dovecot configuration file using the following command
#vi /etc/dovecot/dovecot.conf
# specify protocols = imap imaps pop3 pop3s
protocols = pop3 imap
# uncomment this and change to no.
disable_plaintext_auth = no
pop3_uidl_format = %08Xu%08Xv
Now, create a user to test our pop3 mail with outlook:
#adduser user_name
Note: Always create a separate user to test your mail or ftp.
Restart Dovecot using the following command
#/etc/init.d/dovecot restart
Now, you can use your outlook express to test whether your new mail server is working or not. Just enter username: with password in outlook.
Remember you will NOT be able to send email outside your network, you will be only be able to send within your domain or local network. If you attempt to send email you get “relay access denied” error from outlook express. However, you should have no problems in receiving your email from outlook. Inorder to send email external email you will need to configure SASL authentication as described below.
Configure SASL Authentication with TLS
SASL Configuration + TLS (Simple authentication security layer with transport layer security) used mainly to authenticate users before sending email to external server, thus restricting relay access. If your relay server is kept open, then spammers could use your mail server to send spam. It is very essential to protect your mail server from misuse.
Let us set up SMTP authentication for our users with postfix and dovecot.
Edit the postfix configuration file /etc/postfix/main.cf and enter the few lines to enable authentication of our users
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = yourdomain.com
smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination
smtpd_sasl_security_options = noanonymous
postfix does a chroot so it can’t communicate with saslauthd.
#rm -r /var/run/saslauthd/
#mkdir -p /var/spool/postfix/var/run/saslauthd
#ln -s /var/spool/postfix/var/run/saslauthd /var/run
#chgrp sasl /var/spool/postfix/var/run/saslauthd
#adduser postfix sasl
On the Dovecot side you also need to specify the dovecot authentication daemon socket. In this case we specify an absolute pathname. Refer to this postfix manual here
Edit /etc/dovecot/dovecot.conf file
#vi /etc/dovecot/dovecot.conf
Look for the line that starts with auth default, before that insert the lines below.
auth default {
mechanisms = plain login
passdb pam {
}
userdb passwd {
}
socket listen {
client {
path = /var/spool/postfix/private/auth
mode = 0660
user = postfix
group = postfix
}
}
}
Now, rename previous auth default to auth default2. If you dont rename this then dovecot server will give you error like multiple instances of auth default.
Now restart all the following components of mail server
#/etc/init.d/saslauthd restart
#/etc/init.d/postfix restart
#/etc/init.d/dovecot restart
Test whether your mail server works or not with your outlook express. Configure a user with a user name (without @domain) and make sure that you select my server requires authentication. Under settings select same as incoming mail server
Note:
1. If you dont enable My server requires authentication in outlook you cannot send emails to external recipients and you get relay access denied error.
2. Do not use root login to login to your mail server.
3. Dont forget to create a new user before you authenticate using outlook.
Forwarding Mails
Ever wondered how to forward your mails especially if you are a webmaster managing number of sites. You might need to forward any email sent to your primary email address. Its that easy. Just create a .forward file on your home directory. Insert list of emails addresses separated by commas, where you want to get forwarded.
Login as user and type
echo ‘destination_email_address’ > .forward
or you can use vi to create .forward file. Just Delete .forward file if you dont want any forwarding.
Installing Squirrel Web Mail
Before installing Squirrel Web Mail you need to make sure you have installed apache2 with php support
#aptitude install apache2
#aptitude install libapache2-mod-php5 php5-cli php5-common php5-cgi
#aptitude install squirrelmail
Squirrelmail configuration file is located in: /etc/squirrelmail/ folder. By default all settings are preloaded.
# Run squirrelmail configuration utility as ROOT
/usr/sbin/squirrelmail-configure
Now we want to setup to run under apache. Edit apache configuration file /etc/apache2/apache2.conf and insert the following line
Include /etc/squirrelmail/apache.conf
Restart the webserver using the following command
#/etc/init.d/apache2 restart
Access your webmail using the following link
http://yourdomain or server ip/squirrelmail
Create a separate local user and login as a new user.
Mail Server Logs
Always refer to logs located in /var/log/mail.log so that you can identify what the problem is before you can troubleshoot.
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