PowerShell script to enable litigation hold for all user mailboxes in Exchange

The following PowerShell script will enable litigation hold for all user mailboxes in your environment. The script will work for Exchange 2010 and 2013, both On-Premise or Online.

# First you need to be connected to the Exchange PowerShell.

$pagesize = 100; # The number of mailboxes per loop
$inc = 0; # Start increment value

# Continue until all mailboxes are litigation hold enabled
do {
    Write-Output "Getting mailboxes"
    # Get UserMailboxes that does not have litigation hold enabled
    $mailboxes = Get-Mailbox -Filter {LitigationHoldEnabled -eq $false -and RecipientTypeDetails -eq "UserMailbox"} -ResultSize $pagesize -WarningAction SilentlyContinue
    if($mailboxes) { Write-Output ("Current mailbox count: {0}" -f ($inc += $mailboxes.Count))}
    # Enable litigation hold
    $mailboxes | Set-Mailbox -LitigationHoldEnabled $true -WarningAction SilentlyContinue
} while($mailboxes);

Write-Output "Done"

It is possible to add additional filtering by editing the filter for the Get-Mailbox cmdlet.