I have a couple of questions about zimbra OS and NE collaboration.
I am trying to build a zimbra mail server for 1100 users out of which 100 users would be interested in using outlook. So I would like to get NE for those while I would like to use open source for the rest of them. Now my questions are:
1) If I want to add 100 users on an NE server and 1000 users on an OS server, can I set up the two server instances such that the users on one can seamlessly talk with users on the other server? Also, is it possible to assign same email domain names to both these server instances even if they are within the same network?
2) Also is it possible that I can configure the two hosts in such a way that two specific users on the NE can send/receive emails to only 20 specific users on OS edition and can NOT communicate with anyone else from OS and vice versa? If yes, how can I do that?
3) I saw on the forum that NE is extensible in exactly same way as the OS. Meaning the components which can be extended in OS also comes in the NE such that they can be extended if needed. Is that correct?

Thanks