That depends on the roles the server has been playing, backup systems in place and the state of the 'original' server.
If the server was only handling the mailboxes then you (only) need a full backup of Exchange and restore it on another server.
If the server was also Domain Controller and AD you will have to do a full backup and restore of the entire server.
Moving an Exchange Mailbox Database to Another Server or Storage Group
http://technet.microsoft.com/en-us/library/aa997006(v=exchg.65).aspx
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That depends on the roles the server has been playing, backup systems in place and the state of the 'original' server.
If the server was only handling the mailboxes then you (only) need a full backup of Exchange and restore it on another server.
If the server was also Domain Controller and AD you will have to do a full backup and restore of the entire server.
https://support.iaso.com/support/solutions/articles/70684-a-full-backup-and-restore-of-active-directory-microsoft-exchange-2010-and-microsoft-sql-server-2008
http://www.exchangelog.info/2010/03/backuprestore-of-exchange-2010-using.html
http://msexchangeguru.com/2013/04/04/backup-exec/