Once in a while you may be involved in a situation where you need to preserve E-mails and keep them in an unaltered state. The reasons may vary but the nice thing is that you can easily configure a Litigation Hold within Exchange server to accomplish this. Litigation holds can be set on a per mailbox basis for a given amount of time and can be configured a number of ways. If you are in need of placing all mailboxes on litigation hold you can use the following Exchange PowerShell command:
Get-mailbox | Set-Mailbox -LitigationHoldEnabled $true
This will go through all mailboxes and enable the litigation hold. You can also verify the command was successful by selecting Recipient Configuration, select a mailbox, right click and select properties, click Mailbox Settings, Click Messaging Records Management and selected Properties and you should see a check in the “Enable Litigation Hold” box.
This is a very easy way to place a hold on all mailboxes should you need to do so.