LinuxQuestions.org - problem receiving pop3 mail from postfix mail server

I have installed webmin Version 1.170 on Redhat Linux 9 and am using Virtualmin to administrate my sites along with some custom editting in the DNS etc. As of right now everything works....sorta. i can receive and send mail through Postfix, but only when i am logged in through webmin at port 10000. i cannot read my mail if i log in through Usermin nor can i get my mail using a pop3 client such as Outlook or mail2web.com although these clients will access the server and the server authenticates them. either using Usermin or Outlook or mail2web.com i always get the same thing: no messages in Inbox. however if i log in through webmin and click on "read user mail" and then click on the appropriate mailbox i can read the mail that is sent to the address i set up and sent mail out. can someone suggest an answer for downloading messages through Outlook. NOTE: i have forwarded the following ports accross my firewall: 21, 23, 25, 53, 80, 81, 110