Hai This is Based on our EMAIL Server set up through Home based .
why you need to host your own mail :
There are many reasons to host your own email.Perhaps you don't like the limits placed on you by your current Internet Service Provider. they aren't willing to host the domain you want, or give you the access you want. And if they do fit your needs, they want to charge a small fortune. There are several many ways to accomplish this task. Everyone has their preferred MTA program, but for the purposes of this article, we'll use sendmail. The same can also be done using postfix, or exim. Each approach has its own merits.
MM ok Let started now
What are the Requirements:
I'm going to assume that when setting up your email server, you'll want to do so with your own personalized domain name. While I am not going to explain how to register a domain name, if you're unsure, you can always for an explanation on how to do so. The domain that I'll refer to in this article will be 3ix.com, with the hostname of the machine being server1. I'm also going to assume, at least for now, that your IP address is static, and your inbound and outbound connections on port 25 are unrestricted.
The first thing you'll need will be your physical infrastructure: a computer running Red Hat® Enterprise Linux®, a high-speed Internet connection, and a registered domain name. After you have installed Red Hat Enterprise Linux on your system you will want to make sure the following packages are installed:
·dovecot
.sendmail
.sendmail-cf
.squirrelmail
.perl
.gcc
There are other packages we will need later on .

After you've set up your domain name with your favorite registrar, you will need to configure your Mail Exchanger (MX) record. You will do this through your domain registrar. After you find the page that will allow you to set up your MX record, I recommend you do the following

· Setup the MX record in the format mx.yourdomain.com. So, for our example domain, we would choose "mx.mailjunkie.org" as our MX record.
· Configure your mail exchanger with a priority of 0 (zero).
· Create a hostname/address (A RECORD) that associates mx.mailjunkie.org with the IP address that your ISP has assigned you.After you're done setting this up, you can test to see if it worked by dropping to a shell prompt and issuing the following command. If your setup is correct, you should see some synthesis of :
Please note that it may take some time for the changes you have made to propagate through DNS. If you check immediately after you make these changes and do not see your settings reflected, try a few minutes later.


To Configuring s`endmail:
Ok Now move to configure end mails.. The next step will be setting up and configuring sendmail. The process for doing this is somewhat arduous, so please read all of the information presented before beginning.The file /etc/mail/sendmail.cf is the main configuration file for sendmail. This "cf file" contains the directives that sendmail will operate under. Much more friendly, however, is the file/etc/mail/sendmail.mc. This "mc file" should be the base that you use for making all changes to sendmail's operating parameters. Additionally, the "cf file" is created from the parameters listed in this "mc file". Red Hat has done a wonderful job creating a template for your "mc file" and as such, the bulk of the changes that need to be made are just editing directives that are already present. Below are the directives that you must search for within your "mc file" and change accordingly

Please note: You must replace "your.trusted.smtp.relay" with the name of your ISP's SMTP server. While omitting this change will not prevent your e-mail server from operating properly, there are several filters that are often employed that will block any "at home Cable, xDSL" port 25 connections for fear of spam.After you have made these changes and are back in your server's/etc/mail directory, run the command "make -C /etc/mail". This compiles the "cf file" based on the instructions given in your "mc file". Each time you make a change to your "mc file", you must re-compile your "cf" file by issuing this command

Edit your hosts file:

Sendmail will make use of your /etc/hosts file, so you need to modify it so that mail is routed properly. Edit your /etc/hosts file and include a line that reads:1.2.3.4 server1.mailjunkie.org where 1.2.3.4 is the IP address that is assigned to you by your ISP.