You can perform these moves within a single Exchange forest or across forests.

You may want to move all mailboxes in which the size is greater than a specified limit.

You can move mailboxes to realign based on specific values. Eg, you may want to move a mailbox from one database to another database that has a larger mailbox size limit.

If you need to investigate an issue with a mailbox, you can move that mailbox to a different server.

If  a user moves to a different location, you can move that user's mailbox to a server that is in a site nearer to the new location.

You can move an entire database file to a new location, and then use the Move-Mailbox cmdlet to change the configuration information in Active Directory so that the mailboxes all point to the new location of the database.

You can merge the contents of one mailbox into another mailbox.

After an organizational change such as an acquisition or merger, you may have two separate Exchange forests operating together in a cross-forest scenario. Later, you may want to move mailboxes into a single forest. You can use the Move-Mailbox cmdlet to move mailboxes in this scenario. To reduce the amount of time that users cannot access their mailboxes in a cross-forest move, you can use the Move-Mailbox cmdlet with the AllowMerge parameter.

Before an organizational change such as a divestiture, you may want to move a group of mailboxes to a separate forest. You can use the Move-Mailbox cmdlet to move mailboxes from the existing forest to a new forest. To reduce the amount of time that users cannot access their mailboxes in a cross-forest move, you can use the Move-Mailbox cmdlet with the AllowMerge parameter.

A company may want to separate the administration of Microsoft Exchange from the administration of Microsoft Windows accounts. To do this, you can move mailboxes from a single forest into a resource forest scenario. With this scenario, the Microsoft Exchange mailboxes reside in one forest and their associated Windows user accounts reside in a separate forest.

A company may want to outsource the administration of e-mail and retain the administration of Windows user accounts. To do this, you can move mailboxes from a single forest into a resource forest scenario. With this scenario, the Microsoft Exchange mailboxes reside in one forest and their associated Windows user accounts reside in a separate forest.

A company may want to change from a separated or outsourced e-mail administration model to a model in which e-mail and user accounts can be managed from within the same forest.

		For more information about Exchange Server 2007, check out our Exchange Server 2007 Training Videos
		Exchange Server 2007 Training Videos