Dovecot /postfix with Roundcube WebUI
Make sure you have these packages installed:
yum install php
Download roundcube:
wget http://freefr.dl.sourceforge.net/project/roundcubemail/roundcubemail/0.9.5/roundcubemail-0.9.5.tar.gz
For newest version refer to: http://roundcube.net/