In Exchange 2010, you can use Multi-Mailbox Search to search mailboxes for e-Discovery or similar purposes. To preserve data in user mailboxes and protect its integrity, you can place a mailbox on Litigation Hold (also known as legal hold). This prevents mailbox items from being purged from the Store, without impacting user workflow. Additionally, when a mailbox is on litigation hold, a process known as copy-on-write (yes, COW) preserves a copy of the original item when a modification is made to certain item properties.
Note, COW also kicks in for a mailbox when you enable Single Item Recovery – check out RS4’s (also known as Ross Smith IV) post Single Item Recovery in Exchange Server 2010 and Understanding Recoverable Items in Exchange 2010 documentation for details.
Read more at source: http://blogs.technet.com/b/exchange/archive/2011/05/25/exchange-2010-discovery-modify-the-maximum-number-of-mailboxes-searched-at-a-time.aspx
Cheers,
Anderson Patricio
http://blogs.msexchange.org/patricio
Twitter: @apatricio
