Email servers

This section discusses email servers. (Email clients are discussed in the Client Applications section under Email ):

Which email server to use?
Postfix configuration overview
Using Postfix
Adding email access from a browser
Where to get more information

Which email server to use?

After decades of running sendmail, we moved to postfix since postfix is much easier to configure than sendmail and its performance is very good.

Other possibilities worth checking out:

The rest of this page discusses configuring and using postfix.

Postfix configuration overview

The postfix web site is: http://www.postfix.org. You can download postfix package from rpmfind or install postfix from the Red Hat 9 CDs. To install postfix:

rpm -iv postfix-1.1.11-5.i386.rpm

If you were previously running sendmail: Copy over the updated /etc/aliases file into /etc/aliases and then type: newaliases

The main postfix configuration file is /etc/postfix/main.cf. Edit the file. It is commented very well and tells you what to customize for your site.

Then start postfix:

/etc/init.d/postfix start

Then make postfix automatically start every time the system boots:

chkconfig --add postfix
    This command adds postfix symbolic links into the /etc/rc.d file
    structure.
ntsysv
    Use the down arrow key to move down to postfix
    and then a space to put an asterisk next to postfix
    and then a tab to get to OK then press ENTER to
    save the changes.

Using Postfix

The email clients are the main ones using postfix. However, as the postfix administrator, you may want to check on the mail quese, flush the queues, etc.:

To delete messages from the queue:

mailq postsuper -d message-id

Flush the queue (immediately try to send any messages in the queue):

postfix flush

Adding email access from a browser

You can add email access to your site (similar to yahoo mail which is accessible via the web) using Squirrel Mail. You can get an idea of the web mail interface by looking at screen images of squirrel mail.

The requirements for running squirrel mail are:

Your web server must be configured to use PHP. The default Red Hat 9 web server has the web server configured for PHP already so this shouldn't be a problem.
Install the IMAP4 server from the Red Hat CDs or through rpmfind.

After the above is finished, the you can start installing and configuring squirrel mail.

Download Squirrel mail (pick the .bz2 one since it's compressed the most).
Uncompress and extract squirrel mail into a directory that is accessible by the apache web server:
```
cd /var/www/html
mkdir squirrel
cd squirrel
bzcat squirrelmail*bz2 | tar xvf -
```

Create directories to be used for attachments and user data:

mkdir -p /export/squirrel/data
mkdir -p /export/squirrel/attachments
cd /export/squirrel
chgrp -R apache attachments data
chmod 730 attachments

Edit the config/config.php file, and set the $data_dir and $attachment_dir to the same as the squirrel directory:


...
$data_dir                 = '/export/squirrel/data/';
$attachment_dir           = '/export/squirrel/attachments/';
...

Enable file_uploads in the php.ini file:
```
...
file_uploads = On
...  
```

Create a file named /var/www/html/squirrel/.htaccess with the following contents:

AddType application/php4script .php
Action application/php4script /cgi-bin/php

Restart the web server so it will allow you to send mail through the squirrel mail browser interface. (Reading mail works fine without restarting the web server, but sending email doesn't work until you restart the web server.)
```
/etc/init.d/httpd restart
```
From a browser, access squirrelmail with a URL similar to: http://yourservername/squirrelmail

Where to get more information

Linux Quick Reference Home
Linux Migration Home