How to install and configure a mail server using Postfix + Dovecot + squirrelmail in linux

This post helps to install and configure a mail server with postfix as MTA[ (Mail Transfer agent), Dovecot as MDA (Mail Delivery Agent) and Squirrel mail as MUA (Mail User
Agent). This is a simple basic configuration without much advanced configurations. This is tested in Redhat linux and will also work in other redhat disrtos like 
fedora, centos etc. 


Assuming you have a configured yumserver. Else use the rpms.
#yum install postfix* dovecot* Squirrelmail*

Steps

1. Configure the DNS eg: example.com

2. Select the defalt MTA as postfix. Most systems it will be Sendmail.

#alternatives     --config    mta
Select postfix.

3. open the configuration file of Postfix and edit the following.

#vi /etc/postfix/main.cf
edit the following

 1. my domain
 2. my hostname
 3. inet_interfaces

and reload the service.

4. Configure the Squirrel mail
#cd /usr/share/squirrelmail/config/
run the perl file
#./conf.pl

Give
 1.Domain name
 2.host name [FQDN]
 3.protocol

5. Configure the dovecot
#vi /etc/dovecot.conf

protocols = imap

save it and restart the service.

#service dovecot restart
#chkconfig dovecot on

6. Add the MX entry to DNS. Dont fotget to give the priority.

7. Resolve the hostname in /etc/hosts.

8. Start the httpd [apache]

9. Thats it. you can now access the webmail through

http://example.com/webmail