Configure Dovecot or Courier and Postfix or QMail on CentOS Linux 5.9

We have just setup a rehat 13.9 virtual server (Kloxo Webmin QuickMail Courier seem all installed) and we can get mail via Roundcube - but not outlook. We have around 4 domain names (only 1 is live at the moment) each with one or two email accounts that are all empty. Would like your recommendations to setup our mailserver - Dovecot vs Courier vs ? and then you to setup our mailserver for us We urgently need to get our email working for POP/IMAP access via Outlook and setup a backup routine. Can give you root access and more details. If you can help please respond with your estimate. Need work done today. with kind regards Trevor