Exports all Public Folders and System Folders. If the script is interrupted, just run it again and it will resume.

Export-PublicFolderHierarchy.ps1

[CmdletBinding()]
param (
    [Parameter()]
    [string[]]
    $Properties = @("Identity", "EntryId", "DumpsterEntryId", "FolderSize", "FolderClass"),

    [Parameter()]
    [string]
    $OutputFile = "$PSScriptRoot\PFHierarchy.csv"
)

$ErrorActionPreference = "Stop"
$script:progressCount = 0
$sw = New-Object System.Diagnostics.Stopwatch
$sw.Start()
$progressParams = @{
    Activity = "Exporting public folder hierarchy"
}

$entryIdsAlreadyExported = New-Object 'System.Collections.Generic.HashSet[string]'

if (Test-Path $OutputFile) {
    $OutputFile | Import-Csv | ForEach-Object {
        [void]$entryIdsAlreadyExported.Add($_.EntryId)
        $script:progressCount++
    }

    Write-Host "Loaded $script:progressCount folders from $OutputFile. Resuming export."
}

function GetSubfoldersRecursive {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [object]
        $Folder
    )

    if ($sw.ElapsedMilliseconds -gt 1000) {
        $sw.Restart()
        Write-Progress @progressParams -CurrentOperation $Folder.Identity -Status $script:progressCount
    }

    if (-not $entryIdsAlreadyExported.Contains($Folder.EntryId)) {
        $children = Get-PublicFolder $Folder.EntryId -GetChildren
        foreach ($child in $children) {
            GetSubfoldersRecursive $child
            $child | Select-Object $Properties | Export-Csv $OutputFile -Append -Force
            $script:progressCount++
        }
    }
}

$ipmSubtree = Get-PublicFolder

GetSubfoldersRecursive $ipmSubtree

$nonIpmSubtree = Get-PublicFolder \non_ipm_subtree

GetSubfoldersRecursive $nonIpmSubtree

Write-Host "Done!"