安裝:
# yum install squirrelmail

重新啟動 Apache:
# /etc/init.d/httpd restart

設定 SquirrelMail:
# /usr/share/squirrelmail/config/conf.pl

必須告訴 SquirreMail 使用 Courier-IMAP/-POP3!

SquirrelMail Configuration : Read: config.php (1.4.0)
———————————————————
Main Menu –
1.  Organization Preferences
2.  Server Settings
3.  Folder Defaults
4.  General Options
5.  Themes
6.  Address Books
7.  Message of the Day (MOTD)
8.  Plugins
9.  Database
10. Languages

D.  Set pre-defined settings for specific IMAP servers

C   Turn color off
S   Save data
Q   Quit

Command >> <– D

SquirrelMail Configuration : Read: config.php
———————————————————
While we have been building SquirrelMail, we have discovered some
preferences that work better with some servers that don’t work so
well with others.  If you select your IMAP server, this option will
set some pre-defined settings for that server.

Please note that you will still need to go through and make sure
everything is correct.  This does not change everything.  There are
only a few settings that this will change.

Please select your IMAP server:
    bincimap    = Binc IMAP server
    courier     = Courier IMAP server
    cyrus       = Cyrus IMAP server
    dovecot     = Dovecot Secure IMAP server
    exchange    = Microsoft Exchange IMAP server
    hmailserver = hMailServer
    macosx      = Mac OS X Mailserver
    mercury32   = Mercury/32
    uw          = University of Washington’s IMAP server

    quit        = Do not change anything
Command >> <– courier

SquirrelMail Configuration : Read: config.php
———————————————————
While we have been building SquirrelMail, we have discovered some
preferences that work better with some servers that don’t work so
well with others.  If you select your IMAP server, this option will
set some pre-defined settings for that server.

Please note that you will still need to go through and make sure
everything is correct.  This does not change everything.  There are
only a few settings that this will change.

Please select your IMAP server:
    bincimap    = Binc IMAP server
    courier     = Courier IMAP server
    cyrus       = Cyrus IMAP server
    dovecot     = Dovecot Secure IMAP server
    exchange    = Microsoft Exchange IMAP server
    hmailserver = hMailServer
    macosx      = Mac OS X Mailserver
    mercury32   = Mercury/32
    uw          = University of Washington’s IMAP server

    quit        = Do not change anything
Command >> courier

              imap_server_type = courier
         default_folder_prefix = INBOX.
                  trash_folder = Trash
                   sent_folder = Sent
                  draft_folder = Drafts
            show_prefix_option = false
          default_sub_of_inbox = false
show_contain_subfolders_option = false
            optional_delimiter = .
                 delete_folder = true

Press any key to continue… <– press Enter key

SquirrelMail Configuration : Read: config.php (1.4.0)
———————————————————
Main Menu –
1.  Organization Preferences
2.  Server Settings
3.  Folder Defaults
4.  General Options
5.  Themes
6.  Address Books
7.  Message of the Day (MOTD)
8.  Plugins
9.  Database
10. Languages

D.  Set pre-defined settings for specific IMAP servers

C   Turn color off
S   Save data
Q   Quit

Command >> <–S

Data saved in config.php
Press enter to continue… <– press Enter key

SquirrelMail Configuration : Read: config.php (1.4.0)
———————————————————
Main Menu –
1.  Organization Preferences
2.  Server Settings
3.  Folder Defaults
4.  General Options
5.  Themes
6.  Address Books
7.  Message of the Day (MOTD)
8.  Plugins
9.  Database
10. Languages

D.  Set pre-defined settings for specific IMAP servers

C   Turn color off
S   Save data
Q   Quit

Command >> <–Q

Exiting conf.pl.
You might want to test your configuration by browsing to
http://your-squirrelmail-location/src/configtest.php
Happy SquirrelMailing!

最後設定,編輯 /etc/squirrelmail/config_local.php:
# vi /etc/squirrelmail/config_local.php

/**
* Local config overrides.
*
* You can override the config.php settings here.
* Don’t do it unless you know what you’re doing.
* Use standard PHP syntax, see config.php for examples.
*
* @copyright © 2002-2006 The SquirrelMail Project Team
* @license http://opensource.org/licenses/gpl-license.php GNU Public License
* @version $Id: config_local.php,v 1.2 2006/07/11 03:33:47 wtogami Exp $
* @package squirrelmail
* @subpackage config
//$default_folder_prefix = 』; # 將此行註解

測試:
依照郵件伺服設定,瀏覽器輸入 http://主機名稱/webmailhttp://主機IP/webmail 連結至 SquirrelMail。