Winforms GUI that displays Exchange Online public folders in a tree view with options for adding and/or modifying existing permissions.

PublicFolderPermissionsManager.ps1

# Optionally, connect to Exchange Online if not already connected:
# Import-Module ExchangeOnlineManagement

if (-not (get-command get-mailbox -ErrorAction SilentlyContinue) ) {
    Connect-ExchangeOnline
} 

# Load required .NET assemblies for WinForms
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing

# Define permission options based on Microsoft's public folder permission levels
$permissionOptions = @("Owner", "PublishingEditor", "Editor", "PublishingAuthor", "Author", "NonEditingAuthor", "Reviewer", "Contributor", "None")

# Global variable to hold the current folder path
$Global:currentFolder = $null

# Function to refresh the permissions ListView for the currently selected folder
function Refresh-Permissions {
    if (-not $Global:currentFolder) { return }
    $listView.Items.Clear()
    try {
        $permissions = Get-PublicFolderClientPermission -Identity $Global:currentFolder
        foreach ($perm in $permissions) {
            $user = $perm.User.ToString()
            $access = $perm.AccessRights -join ", "
            $item = New-Object System.Windows.Forms.ListViewItem($user)
            $item.SubItems.Add($access)
            $listView.Items.Add($item)
        }
    }
    catch {
        [System.Windows.Forms.MessageBox]::Show("Error retrieving permissions for folder: $Global:currentFolder","Error",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Error)
    }
}

# Create the main form
$form = New-Object System.Windows.Forms.Form
$form.Text = "Exchange Online Public Folders Manager"
$form.Size = New-Object System.Drawing.Size(900,600)
$form.StartPosition = "CenterScreen"

# Create left panel for the TreeView (fixed width)
$panelLeft = New-Object System.Windows.Forms.Panel
$panelLeft.Dock = [System.Windows.Forms.DockStyle]::Left
$panelLeft.Width = 250
$panelLeft.Padding = New-Object System.Windows.Forms.Padding(10)

# Create right panel for controls (fixed width)
$panelRight = New-Object System.Windows.Forms.Panel
$panelRight.Dock = [System.Windows.Forms.DockStyle]::Right
$panelRight.Width = 250
$panelRight.Padding = New-Object System.Windows.Forms.Padding(10)

# Create center panel for the ListView (fills remaining space)
$panelCenter = New-Object System.Windows.Forms.Panel
$panelCenter.Dock = [System.Windows.Forms.DockStyle]::Fill
$panelCenter.Padding = New-Object System.Windows.Forms.Padding(10)

# ---------------------------
# Left Panel - TreeView for Public Folders
# ---------------------------
$treeView = New-Object System.Windows.Forms.TreeView
$treeView.Dock = [System.Windows.Forms.DockStyle]::Fill
$panelLeft.Controls.Add($treeView)

# ---------------------------
# Center Panel - ListView for Permissions
# ---------------------------
$listView = New-Object System.Windows.Forms.ListView
$listView.Dock = [System.Windows.Forms.DockStyle]::Fill
$listView.View = [System.Windows.Forms.View]::Details
$listView.FullRowSelect = $true
$listView.GridLines = $true
$listView.Columns.Add("User",150) | Out-Null
$listView.Columns.Add("Permission Level",130)  | Out-Null
$panelCenter.Controls.Add($listView)

# ---------------------------
# Right Panel - Controls for Modifying Permissions
# ---------------------------
# Note: Use relative positioning within the right panel.
# The panel's width is fixed (250), so set control widths to fill (minus padding).
$controlWidth = $panelRight.Width - 20  # subtracting left/right padding

$btnRemove = New-Object System.Windows.Forms.Button
$btnRemove.Location = New-Object System.Drawing.Point(10,20)
$btnRemove.Size = New-Object System.Drawing.Size($controlWidth,30)
$btnRemove.Text = "Remove Selected User"
$btnRemove.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($btnRemove)

$lblUpdate = New-Object System.Windows.Forms.Label
$lblUpdate.Location = New-Object System.Drawing.Point(10,70)
$lblUpdate.Size = New-Object System.Drawing.Size($controlWidth,20)
$lblUpdate.Text = "New Permission (Update):"
$lblUpdate.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($lblUpdate)

$cmbUpdatePermission = New-Object System.Windows.Forms.ComboBox
$cmbUpdatePermission.Location = New-Object System.Drawing.Point(10,95)
$cmbUpdatePermission.Size = New-Object System.Drawing.Size($controlWidth,25)
$cmbUpdatePermission.DropDownStyle = 'DropDownList'
$cmbUpdatePermission.Items.AddRange($permissionOptions)
$cmbUpdatePermission.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($cmbUpdatePermission)

$btnUpdate = New-Object System.Windows.Forms.Button
$btnUpdate.Location = New-Object System.Drawing.Point(10,130)
$btnUpdate.Size = New-Object System.Drawing.Size($controlWidth,30)
$btnUpdate.Text = "Update Selected User"
$btnUpdate.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($btnUpdate)

$lblAddHeader = New-Object System.Windows.Forms.Label
$lblAddHeader.Location = New-Object System.Drawing.Point(10,180)
$lblAddHeader.Size = New-Object System.Drawing.Size($controlWidth,20)
$lblAddHeader.Text = "Add New User:"
$lblAddHeader.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($lblAddHeader)

$lblNewUser = New-Object System.Windows.Forms.Label
$lblNewUser.Location = New-Object System.Drawing.Point(10,210)
$lblNewUser.Size = New-Object System.Drawing.Size(80,20)
$lblNewUser.Text = "User:"
$lblNewUser.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left
$panelRight.Controls.Add($lblNewUser)

$txtNewUser = New-Object System.Windows.Forms.TextBox
$txtNewUser.Location = New-Object System.Drawing.Point(100,210)
$txtNewUser.Size = New-Object System.Drawing.Size(($controlWidth - 90),25)
$txtNewUser.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($txtNewUser)

$lblNewPerm = New-Object System.Windows.Forms.Label
$lblNewPerm.Location = New-Object System.Drawing.Point(10,245)
$lblNewPerm.Size = New-Object System.Drawing.Size(80,20)
$lblNewPerm.Text = "Permission:"
$lblNewPerm.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left
$panelRight.Controls.Add($lblNewPerm)

$cmbNewPermission = New-Object System.Windows.Forms.ComboBox
$cmbNewPermission.Location = New-Object System.Drawing.Point(100,245)
$cmbNewPermission.Size = New-Object System.Drawing.Size(($controlWidth - 90),25)
$cmbNewPermission.DropDownStyle = 'DropDownList'
$cmbNewPermission.Items.AddRange($permissionOptions)
$cmbNewPermission.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($cmbNewPermission)

$btnAdd = New-Object System.Windows.Forms.Button
$btnAdd.Location = New-Object System.Drawing.Point(10,280)
$btnAdd.Size = New-Object System.Drawing.Size($controlWidth,30)
$btnAdd.Text = "Add New User"
$btnAdd.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left -bor [System.Windows.Forms.AnchorStyles]::Right
$panelRight.Controls.Add($btnAdd)

# ---------------------------
# Add panels to the form
# Order is important when docking. The Fill-docked panel should be added first.
$form.Controls.Add($panelCenter)
$form.Controls.Add($panelRight)
$form.Controls.Add($panelLeft)

# ---------------------------
# Populate the TreeView with Public Folders
# ---------------------------
try {
    $publicFolders = Get-PublicFolder -Identity "\" -Recurse -ResultSize Unlimited
}
catch {
    [System.Windows.Forms.MessageBox]::Show("Error retrieving public folders. Please ensure you are connected to Exchange Online.","Error",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Error)
    return
}

# Hashtable to store folder path => TreeNode mappings
$treeNodes = @{}
$sortedFolders = $publicFolders | Sort-Object { ($_.Identity.ToString().TrimEnd("\") -split "\\").Count }

foreach ($folder in $sortedFolders) {
    $folderPath = $folder.Identity.ToString()
    if ($folderPath -eq "\") {
        $node = New-Object System.Windows.Forms.TreeNode("Public Folders")
        $node.Tag = $folderPath
        $treeView.Nodes.Add($node) | Out-Null
        $treeNodes[$folderPath] = $node
    }
    else {
        $folderName = $folder.Name
        $index = $folderPath.LastIndexOf("\")
        if ($index -le 0) {
            $parentPath = "\"
        }
        else {
            $parentPath = $folderPath.Substring(0, $index)
            if ($parentPath -eq "") { $parentPath = "\" }
        }
        $node = New-Object System.Windows.Forms.TreeNode($folderName)
        $node.Tag = $folderPath
        if ($treeNodes.ContainsKey($parentPath)) {
            $treeNodes[$parentPath].Nodes.Add($node) | Out-Null
        }
        else {
            $treeView.Nodes.Add($node) | Out-Null
        }
        $treeNodes[$folderPath] = $node
    }
}

# When a node is selected, update the current folder and refresh permissions
$treeView.Add_AfterSelect({
    param($sender, $e)
    $Global:currentFolder = $e.Node.Tag
    Refresh-Permissions
})

# ---------------------------
# Button Event Handlers
# ---------------------------
# Remove Selected User
$btnRemove.Add_Click({
    if (-not $Global:currentFolder) {
        [System.Windows.Forms.MessageBox]::Show("No folder selected.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    if ($listView.SelectedItems.Count -eq 0) {
        [System.Windows.Forms.MessageBox]::Show("No user selected in the permissions list.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    $selectedUser = $listView.SelectedItems[0].Text
    try {
        Remove-PublicFolderClientPermission -Identity $Global:currentFolder -User $selectedUser -Confirm:$false
        [System.Windows.Forms.MessageBox]::Show("User '$selectedUser' removed successfully.","Info",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Information)
        Refresh-Permissions
    }
    catch {
        [System.Windows.Forms.MessageBox]::Show("Error removing user '$selectedUser'.","Error",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Error)
    }
})

# Update Selected User's Permissions
$btnUpdate.Add_Click({
    if (-not $Global:currentFolder) {
        [System.Windows.Forms.MessageBox]::Show("No folder selected.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    if ($listView.SelectedItems.Count -eq 0) {
        [System.Windows.Forms.MessageBox]::Show("No user selected in the permissions list.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    $newPermission = $cmbUpdatePermission.Text.Trim()
    if ([string]::IsNullOrEmpty($newPermission)) {
        [System.Windows.Forms.MessageBox]::Show("Please select a new permission level from the dropdown.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    $Script:selectedUser = $listView.SelectedItems[0].Text
    try {
        # Remove and then re-add with the new permission level
        Remove-PublicFolderClientPermission -Identity $Global:currentFolder -User $selectedUser -Confirm:$false
        Add-PublicFolderClientPermission -Identity $Global:currentFolder -User $selectedUser -AccessRights $newPermission
        [System.Windows.Forms.MessageBox]::Show("User '$selectedUser' updated to '$newPermission'.","Info",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Information)
        Refresh-Permissions
    }
    catch {
        [System.Windows.Forms.MessageBox]::Show("Error updating user '$selectedUser' permission to $($newPermission).`n$($_.Exception.Message)","Error",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Error)
    }
})

# Add New User
$btnAdd.Add_Click({
    if (-not $Global:currentFolder) {
        [System.Windows.Forms.MessageBox]::Show("No folder selected.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    $newUser = $txtNewUser.Text.Trim()
    $newPermission = $cmbNewPermission.Text.Trim()
    if ([string]::IsNullOrEmpty($newUser) -or [string]::IsNullOrEmpty($newPermission)) {
        [System.Windows.Forms.MessageBox]::Show("Please enter both a user and select a permission level.","Warning",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Warning)
        return
    }
    try {
        Add-PublicFolderClientPermission -Identity $Global:currentFolder -User $newUser -AccessRights $newPermission
        [System.Windows.Forms.MessageBox]::Show("User '$newUser' added with '$newPermission'.","Info",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Information)
        Refresh-Permissions
    }
    catch {
        [System.Windows.Forms.MessageBox]::Show("Error adding user '$newUser'.","Error",[System.Windows.Forms.MessageBoxButtons]::OK,[System.Windows.Forms.MessageBoxIcon]::Error)
    }
})

# Ensure the form gets focus when shown and run the form
$form.Add_Shown({ $form.Activate() })
[System.Windows.Forms.Application]::EnableVisualStyles();
[void] $form.ShowDialog()