I have setup an Ubuntu 8.04 Server, with Bind9, SSH, Postfix, Courier IMAP/POP etc., as per step-by-step guide http://www.howtoforge.org/perfect-server-ubuntu8.04-lts

Moreover, I have setup ISPConfig also on this server. (I don't think it was needed actually)

My server works fine, thanks to all guys who helped me setting up the same.

Now, I want this server to do some extra tasks as under:

1. I want ubuntu server to collect mails from mail boxes provided by my ISP, and forward them to local clients connected to ubuntu server only. (they do not have internet access)

2. Local clients connected to ubuntu server should be able to send mail through mailservers provided by ISP. (if I use SMTP service of ubuntu server, most of mail returns giving error "550 5.7.1 Client host rejected: cannot find your reverse hostname")

Note: I not have static IP for my ubuntu server.

Please guide me setting up this.

Thanks in advance.