I currently use a Exchange 2003 server on my Admin network (we still use 2 separate domains, joined by a partial trust - not all curric servers can access admin).

I am looking to replace this with better hardware but I have a few questions.

1. How do I move the mailboxes?
2. If in want 2 people to access a mailbox from separate domains, what is the best way to set it up? I will want to have the ability to manage it from either network (if possible), add mailboxes from either domain, etc etc.

I will hopefully be upgrading the servers within the next few years and will be moving to one flat domain (curric) eventually. I was wondering of setting it up on the curric, but how can I allow it accross domains?

3. We currently use the LGfL Exchange servers, but as they have not enabled full Exchange intercession yet. I was thinking of having staff setup on our local exchange server and pupils still on LGfL. We all use the same @highschool.co.uk email addresses, but is there a way to differentiate between different groups and have staff on ours and pupils on another server? IE the LGfL Staff group gets forwarded down to us. Can this apply to specific users too?

4. How many mail boxes are best per server? We have around 100 staff, but was initially thinking just setting up the Senior staff and the ICT Staff on the local exchange, but eventually it could be anything up to 1000 users. Will this be ok on a dual Xeon with 2gb ram?