Thanks for your quick reply.
Well, I reinstalled Fedora 11 and installing each applications piece by piece. I went to courier's main page and downloaded the courier-imap and other else. I am trying to read their instruction on how to install it and make it work with postfix. Fedora 11 is already loaded with all these new versions of packages, except courier-imap, courier-authlib. So I downloaded these manually and installing it manually and see what is going to happen.
I hope you can figure this out sooner and share some inputs for these problems. I like Fedora 11 but it removed some features that I like with Fedora 8. I am keeping Fedora 8 with some of my servers.
But can we use just dovecot to take the place of courier? Or is there another we can use as a good substitute for courier?
Please update us with any new light you may find about this courier.