Problem with Mail Server CentOS 6.5 (Postfix, Dovecot)

[JEWEL AHMMED <jewelbdx@xxxxxxxxx>]

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 )
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