You have mailboxes on one server and need to move them to another.
For Exchange Server 2003:
Log on to any machine in your domain that has the Exchange management tools installed.
Open the ADUC snap-in (Users and Computers.msc).
Locate the container that holds the mailbox you want to move.
Select the mailboxes you want to move, then right-click any one of them and choose the Exchange Tasks command.
The Exchange Task Wizard will appear. (You may see a welcome page first; if so, click Next to dismiss it.)
From the Available Tasks window, choose Move Mailbox and click Next.
The Move Mailbox page will appear, showing the server where the target mailbox is currently stored.
Choose the target mailbox server from the Server drop-down listing; it will list only those servers that you can move the mailbox to. For example, if you have front-end servers, they won't appear in the drop-down listing even if they have mailbox stores.
Choose the mailbox database that you want to hold the mailboxes; the contents of the Mailbox Store database will change to reflect available databases on the selected server.
Click Next and then click Finish.
Wait while the mailboxes are moved.
-move switch allows you
to specify a target location for the specified mailbox:
> exchmbx -b <
<server> as a
NetBIOS or FQDN; the
<mailboxDatabase> values ...