How to integrate fetch mail into zimbra mail

[tun_omo]

HI
I have a zimbra mail server running on ubuntu Linux server with bind properly configured on it. I can receive and send mail locally within my local network, which is what it was intended to do. but moving a step further, my company has a mail server with an external Isp. here comes the questions:
1. how can i configure fetch mail to go fetch our mails from our external ISP and drop it on Zimbra the local or intranet server.

2.how do i configure zimbra to drop this external mail into individual local emails, i.e Zimbra local internal mails.

[phoenix]

There are several threads in the forums that cover the use of Fetchmail, do a forum search for the word 'fetchmail'