I flow the tutorials... But, I can't success.. :(

Please check this links:

http://www.unixmen.com/install-postfix-mail-server-with-dovecot-and-squirrel...

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 )