Add a new exchange server in existing organization.
http://www.petri.co.il/forums/showthread.php?t=9955MS Article Ref: with checklists etc.
http://technet.microsoft.com/en-us/library/bb123643(EXCHG.65).aspxMove Mailboxes
http://www.msexchange.org/tutorials/Exchange_2003_Move_Mailbox_Wizard.htmlhttp://support.microsoft.com/kb/821829--
I think the better idea is to install RPC/HTTPS on the main exchange server and have the remote users connect to Exchange using RPC/HTTPS
This will centralize a lot of things from exchange point of view. - backups / managability / centralized administration.
Backingup remote mailboxes over internet = real bad.
On top of that if you are downloading mails over VPN - there are other tweaks you need to do do regarding MTU etc.
Also you have to configure no-defrag of packets.
RPC/HTTPS
http://www.msexchange.org/tutorials/Implementing-RPC-over-HTTPS-single-Exchange-Server-2003-environment.htmlhttp://www.petri.co.il/how-can-i-configure-rpc-over-https-on-exchange-2003-single-server-scenario.htmHope this helps.