I flow the tutorials... But, I can't success.. :( Please check this links: http://www.unixmen.com/install-postfix-mail-server-with-dovecot-and-squirrelmail-on-centos-6-4/ http://www.krizna.com/centos/setup-mail-server-in-centos-6/#postfix http://linuxdrops.com/install-postfix-with-cyrus-on-centos-rhel-fedora/ Please tell me which is good ? & Do I need to change any command or step? I want to use mail client for sending & receiving mail Eg. Thunderbird ( SMTP, IMAP, POP3 )