SquirrelMail Configuration Easy Steps (SquirrelMail + Sendmail + Apache On RedHat/CentOS/Fedora)

This tutorial explains how you can install and configure SquirrelMail on a RedHat/CentOS/Fedora based mail server which uses Sendmail and Apache.

Scenario:

Primary Mail Server:  linuxbox4 (192.168.0.14)
Domain Name:     abc.com
Trusted IP Pool:     192.168.0.0/24

Note:  Replace domain name and system name and IP according to your scenario.


Prerequisites:

1.  DNS is configured with proper MX record.
2.  All necessary packages/ softwares are installed.


Step 1:

Configure all service to start at boot time.

chkconfig sendmail on
chkconfig httpd  on
chkconfig dovecot on


Step 2:

Configure /etc/hosts file. In this scenario /etc/hosts file should look like this:

192.168.0.14    linuxbox4   www.abc.com



Step 3:

Outgoing Mail Server Configuration (Sendmail):

Open /etc/mail/sendmail.mc file and change the following two lines.

From:

DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
FEATURE(`accept_unresolvable_domains')dnl

To:

dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
dnl FEATURE(`accept_unresolvable_domains')dnl

Save and exit.

- First line here enables sendmail to receive incoming emails on all installed the NICs. Otherwise mail server would only be able to receive mails from it.
Click here to find out more!

- Second line here tells sendmail, do not receive emails from mail servers whose PTR record is not configured in DNS server. This is a basic level SPAM control settings in sendmail.

Generate sendmail.cf file from sendmail.mc file.

m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf


Step 4:

Allow RELAY for trusts (organization's) IP addresses that you want to permit sending emails using this mail server. Open /etc/mail/access in this file we specify all those addresses that will be sending emails through this mail server. At the end of this file add the following line:

192.168.0 RELAY

Save and exit and convert this text database into DB format by following command.

makemap hash access.db < access


Step 5:

Tell sendmail that it will be acting as a primary mail server for "abc.com" domain. We do this by adding domain name in /etc/mail/local-host-names. If this server is acting as a mail server for more then one domains then add names of all of the domains in this file on separate line. Open /etc/mail/local-host-names and add "abc.com" at the end of this file.

Note: A mail server can act as a primary mail server for more then one domains at the same time and as well as can act as a primary and secondary mail server for more than one domain at the same time.


Step 6:

All system users are mail users as well. Now create mail only users.

useradd -s /usr/sbin/smrsh mailuser1
useradd -s /usr/s2n/smrsh mailuser1

Also set their passwords:

passwd mailuser1
passwd mailuser2


Step 7:

Finally restart sendmail service.

service sendmail restart