Exchange Server 2010 mailbox export with splitting by year if the mailbox is too large.

salvage.ps1

# Exchange Server 2010 eats up extreme amounts of memory when exporting large
# mailboxes. This script attempts to provide a workaround by splitting exports
# of mailboxes that are larger than 10 GB into yearly chunks.
#
# This script will obviously create a few PSTs that are empty. You can easily
# spot these by their file size. Empty PSTs are 265 KB in size.
#
# It worked for my one-off use case, but is provided AS-IS and without any
# warranty or guarantees of correctness.

$startyear = 1999 # Email older than 25 years hopefully isn't relevant anymore
# The reason for not just going by the user's creation date
# is that the user may have content in their mailbox from
# before their creation date (someone gave them MSG files,
# they restored from someone else's email archive, etc.)
$destination = '\\server\exports\' # Where to store exports

############################################################################

function Wait-ForExportCompletion
{
    param(
        [Parameter(Mandatory = $true)]
        $reqName
    )

    Write-Host "Exporting $reqName" -NoNewline

    $req = Get-MailboxExportRequest -Name $reqName

    while ($req.Status -ne 'Completed' -and $req.Status -ne 'Failed')
    {
        $exportStats = $req | Get-MailboxExportRequestStatistics

        if ($null -ne $exportStats.PercentComplete)
        {
            try
            {
                $averageTimePerItem = ($exportStats.TotalInProgressDuration.TotalSeconds) / $exportStats.ItemsTransferred
                $itemsRemaining = $exportStats.EstimatedTransferItemCount - $exportStats.ItemsTransferred				
                $predictedRemainingDurationSeconds = $averageTimePerItem * $itemsRemaining
                $predictedRemainingDuration = [TimeSpan]::FromSeconds($predictedRemainingDurationSeconds)
    
                Write-Progress -Activity "Processing $($req.Name)" -Status "$($exportStats.PercentComplete)% Complete. ETA: $($predictedRemainingDuration.ToString()), Remaining: $itemsRemaining" -PercentComplete $exportStats.PercentComplete
            }
            catch
            {
                Write-Progress -Activity "Processing $($req.Name)" -Status 'Initializing' -PercentComplete 0
            }

            Write-Host '.' -NoNewline
        }
        
        Start-Sleep -Seconds 5

        $req = Get-MailboxExportRequest -Name $reqName
    }

    'Done.'

    Write-Progress -Activity "Processing $reqName" -Status 'Export completed.' -PercentComplete 100

    if ($req.Status -eq 'Failed')
    {
        $req | Get-MailboxExportRequestStatistics | Format-List
        throw 'Export failed.'
    }
}

$username = Read-Host 'Enter the mailbox identity'

$mailbox = $null
try
{
    $mailbox = Get-Mailbox -identity $username
}
catch
{
    Write-Error 'Invalid mailbox identity.'
    throw
}

'Determining mailbox size. This may take a while...'

$mailboxsize = $mailbox | Get-MailboxStatistics | Select-Object @{Name = 'TotalItemSizeGB'; Expression = { [math]::Round(($_.TotalItemSize.ToString().Split('(')[1].Split(' ')[0].Replace(',', '') / 1GB), 0) } }

if ($mailboxsize.TotalItemSizeGB -le 10)
{
    'This mailbox is small. Exporting as a single PST file.'

    $reqName = "$username.complete"
    New-MailboxExportRequest -Mailbox $username -Name $reqName -FilePath "$destination\$reqName.pst" | Out-Null

    Wait-ForExportCompletion -reqName $reqName
}
else
{
    'This mailbox is large. It will be split into yearly PST files.'
    $y = $startyear
    $endyear = (Get-Date).Year

    While ($y -le $endyear)
    {
        $start = New-Object DateTime $y, 1, 1
        $end = New-Object DateTime ($y + 1), 1, 1

        $reqName = "$username.email.$y"
        New-MailboxExportRequest -ContentFilter "MessageKind -eq 'Email' -and ((Received -ge '$start') -and (Received -lt '$end') -or (Sent -ge '$start') -and (Sent -lt '$end'))" -Mailbox $username -Name $reqName -FilePath "$destination\$reqName.pst" | Out-Null

        Wait-ForExportCompletion -reqName $reqName

        $y++
    }
    
    # Items that are not email don't have a sent or received property.
    $reqName = "$username.nonemail"
    New-MailboxExportRequest -ContentFilter "MessageKind -ne 'Email'" -Mailbox $username -Name $reqName -FilePath "$destination\$reqName.pst" | Out-Null
    Wait-ForExportCompletion -reqName $reqName
}