Webmail

• http://www.horde.org/
• http://www.xuheki.com
• http://www.squirrelmail.org/
• http://roundcube.net/

extmail

• http://www.extmail.org/forum/
• http://sourceforge.net/projects/extmail/
• http://www.linuxidc.com/Linux/2010-04/25417p3.htm
• http://www.yiyou.org/docs/centos_extmail_01/