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When you delete a public folder using a legacy Outlook client, you can easily restore the deleted folder and it's content using the Recover Deleted Items function. 

Due to a fancy trick implemented in Outlook 2013 and Outlook 2016 the recovered folder will not be recovered using it's full name.

This phenomenon has been verified with Exchange On-Premises and Exchange Online on the server side and Outlook 2013/2016 and Outlook 365 ProPlus.

The following example uses public folders in Exchange Online and Outlook 365 ProPlus.


In this example I will delete and recover a public folder named My Public Folder.

Public folder hierarchy before deletion

After deletion of My Public Folder and it's content, I need to select the original parent folder and click the Recover Deleted Items button in the button bar.

Select original parent folder

Recover Deleted Items

The Recover Deleted Items dialogue opens and we select the deleted item for recovery. The dialogue displays the original name of the deleted folder.

Recover Deleted Items (DE)

After recovering the deleted folder the folder is recovered with the first character only.

Recovered public folder with first character only

That's an annoying result in regards to customer self-care when users restore deleted items on their own behalf.

But wait, there is a solution available.


The solution requires today's primary administrative tool available: PowerShell.

Step 1

Get an overview of public folders currently located in the public folder dumpster

Get-PublicFolder –Identity “\NON_IPM_SUBTREE” –Recurse 

Name             Parent Path
----             -----------


Step 2

Export the list of public folders currently located in the public folder dumpster and find the identity of the deleted public folder you want to recover

Get-PublicFolder –Identity “\NON_IPM_SUBTREE” –Recurse  | fl | Out-File D:\TMP\publicfolderdumpster.txt

publicfolderdumpster.txt excerpt:

RunspaceId                     : 6ce9588e-829b-4592-aedc-85f9a2e2c963
Identity                       : \NON_IPM_SUBTREE\DUMPSTER_ROOT\DUMPSTER_EXTEND\RESERVED_1\RESERVED_1\65722859-366a-4e0
                                 9-81fe-ea576ec7a6f7\My Public Folder
Name                           : My Public Folder
MailEnabled                    : False
MailRecipientGuid              : 
ParentPath                     : \NON_IPM_SUBTREE\DUMPSTER_ROOT\DUMPSTER_EXTEND\RESERVED_1\RESERVED_1\65722859-366a-4e0

Step 3

Recover the deleted public folder to the correct parent target folder

Set-PublicFolder –Identity "\NON_IPM_SUBTREE\DUMPSTER_ROOT\DUMPSTER_EXTEND\RESERVED_1\RESERVED_1\65722859-366a-4e09-81fe-ea576ec7a6f7\My Public Folder" –Path “\TestFolders” –Verbose

As a result the public folder is recovered with it's original name.


There are some other things to consider when recovering deleted modern public folders.

Public folders originally located in the hierarchy root are always recovered to the public folder mailbox holding the primary hierarchy. 

Public folders originally located in the hierarchy root will replace the permissions of child public folders when restored. 

More on these default restore behaviours can be read here.


Nevertheless, enjoy modern public folders.



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Exchange Server 2007Exchange Server 2010Exchange Server 2013Exchange Server 2016Description

This script gathers all public folders created during the last X days and exports the gathered data to a CSV file.

The script is not limited to legacy or modern public folders. It can be used with Exchange Server 2007/2010 and Exchange Server 2013/2016.

Use this script to identify users or departments creating to many folders in the public folder hierarchy. The CSV can be used to provide better guidance on public folder usage or can be used for planning public folder content migrations to other team based solutions (aka Shared Mailboxes, etc.)



# Query legacy public folder server MYPFSERVER01 for all public folders created during the last 31 days
.\Get-NewPublicFolders.ps1 -Days 31 -ServerName MYPFSERVER01 -Legacy

# Query modern public folders for all public folders created during the last 31 days
.\Get-NewPublicFolders.ps1 -Days 31

Version History

  • 1.0, Initial community release





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Exchange Server 2007When you are dealing with legacy public folders and you are still using Exchange Server 2007 you might be interested in the overall size of the data hosting in your public folder hierarchy.

The following script calculates the public folder size based on the public folder statistics output provided by Exchange Server 2007.

# Server name hosting legacy public folders

# Fetch legacy public folder statistics
$Folders = Get-PublicFolderStatistics -server $Server | Where-Object {($_.TotalItemSize -ne "0B")}  

$TotalBytes = 0

# Let's do some string manipulation stuff
ForEach ($Item in $Folders) {
  $TotalItemSize = $Item.TotalItemSize
  $TotalItemSize = [string]$TotalItemSize
  if ( ($TotalItemSize.contains('KB')) ) {
      $TotalItemSize = $TotalItemSize -Replace ('KB','')
      $TotalItemSize = [int]$TotalItemSize * 1024
  $TotalItemSize = $TotalItemSize -Replace ('B','')
  $TotalBytes = [long]$TotalItemSize + [long]$TotalBytes

# Output as GB 
[math]::round($TotalBytes/1Gb, 2)





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Exchange Server 2007Exchange Server 2010Description

This scripts removes or updates users in legacy public folder ACLs. This reduces the likelihood of legacy public folder migration errors due to corrupted ACLs.

When you perform a migration from legacy public folders to modern public folders, you might see the following error as part of the migration reports.

A corrupted item was encountered: Folder ACL

Corrupted items count towards the bad item limit and will not be migrated.

When you take a closer look at the public folder ACLs, you'll see that there will be orphaned users and even users that have not been properly converted during past legacy replications.

In preparation for a modern public folder migration you should cleanup the public folder ACLs from so called zombie users.

Tasks performed by the script:

  • Remove orphaned users listed with SIDs, e.g. NT User:S-1-*
  • Identify ACL user/group with notation NT User:DOMAIN\samAccountName
    • Remove user/group, if object cannot be found in Active Directory
    • Replace user/group, if object can be found in Active Directory


# Validate ACLs on public folder \MYPF and all of it's child public folders on Exchange server EX200701
.\Clean-PublicFolderACL.ps1 -RootPublicFolder "\MYPF" -PublicFolderServer EX200701 -ValidateOnly

# Clean ACLs on public folder \MYPF and all of it's child public folders on Exchange server EX200701
.\Clean-PublicFolderACL.ps1 -RootPublicFolder "\MYPF" -PublicFolderServer EX200701

Version History

  • 1.0, Initial community release
  • 1.1, Fixed group replacement logic
  • 1.2, Script optimzation


Last updated: 2016-12-01



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On November 15, 2016
0 Comment
Updated: 2016-12-20

Migrating legacy public folders (Exchange Server 2010 or older) to modern public folders (Exchange 2013 or newer / Office 365) requires a cleanup of public folders.

There are quite a lot of blog posts and tutorials available describing the general process of migrating legacy public folders to modern public folders.

First you have to identify all public folders having a backslash "\" as part of the public folder name.

Get-PublicFolderDatabase | ForEach {Get-PublicFolderStatistics -Server $_.Server | Where {$_.Name -like "*\*"}}

Just rename those public folders to a name without a backslash.

Another issue might prevent a successful public folder migration: Access Controll Lists (ACL)

This will be the case in public folder hierarchies that go back to the early days of Exchange and have never cleaned up properly during past Exchange migrations.

The cleanup any orphaned Active Directory accounts, run the following PowerShell script.

Get-PublicFolder "\" -Recurse -ResultSize Unlimited | Get-PublicFolderClientPermission | ?{$_.User -like "NT User:S-1-*"} | %{Remove-PublicFolderClientPermission -Identity $_.Identity -User $_.User -Access $_.AccessRights -Confirm:$false}

To cleanup just a single public folder, run the following PowerShell script.

Get-PublicFolder "\My Folder" -Recurse -ResultSize Unlimited | Get-PublicFolderClientPermission | ?{$_.User -like "NT User:S-1-*"} | %{Remove-PublicFolderClientPermission -Identity $_.Identity -User $_.User -Access $_.AccessRights -Confirm:$false}

It should be noted that most of the tutorials have been written using an Exchange Server lab environment with just a few legacy public folders. Therefore, some readers tend to beleive that you only need one modern public folder mailbox. That is not true. In a large legacy public folder infrastructure you will end up with a multiple public folder mailboxes. And the number of mailboxes required to serve the public folder hierarchy.

A larger public folder migration batch using 66 public folder mailboxes looks like this:

Get-MigrationUser -BatchID PFMigration | Get-MigrationUserStatistics | ft -AutoSize

Identity    Batch       Status Items Synced Items Skipped
--------    -----       ------ ------------ -------------
PFMailbox1  PFMigration Synced 91993        16
PFMailbox2  PFMigration Synced 103239       0
PFMailbox46 PFMigration Synced 35034        0
PFMailbox56 PFMigration Synced 22554        0
PFMailbox57 PFMigration Synced 20740        0
PFMailbox58 PFMigration Synced 20122        0
PFMailbox59 PFMigration Synced 7209         0
PFMailbox60 PFMigration Synced 104727       0
PFMailbox61 PFMigration Synced 23278        0
PFMailbox62 PFMigration Synced 9760         0
PFMailbox63 PFMigration Synced 9277         0
PFMailbox65 PFMigration Synced 5870         0
PFMailbox64 PFMigration Synced 5639         0
PFMailbox66 PFMigration Synced 21261        0
PFMailbox50 PFMigration Synced 27889        0
PFMailbox52 PFMigration Synced 14063        0
PFMailbox47 PFMigration Synced 29476        0
PFMailbox54 PFMigration Synced 24283        0
PFMailbox55 PFMigration Synced 4646         0
PFMailbox51 PFMigration Synced 59943        0
PFMailbox53 PFMigration Synced 30052        0
PFMailbox49 PFMigration Synced 22746        0
PFMailbox48 PFMigration Synced 16941        0
PFMailbox18 PFMigration Synced 34307        0
PFMailbox19 PFMigration Synced 4523         0
PFMailbox11 PFMigration Synced 100409       0
PFMailbox6  PFMigration Synced 116655       0
PFMailbox4  PFMigration Synced 55240        5
PFMailbox12 PFMigration Synced 37790        0
PFMailbox3  PFMigration Synced 113842       2
PFMailbox22 PFMigration Synced 46416        0
PFMailbox23 PFMigration Synced 37387        0
PFMailbox13 PFMigration Synced 231845       1
PFMailbox7  PFMigration Synced 82859        0
PFMailbox20 PFMigration Synced 65818        0
PFMailbox21 PFMigration Synced 32270        0
PFMailbox9  PFMigration Synced 46609        0
PFMailbox14 PFMigration Synced 30637        0
PFMailbox38 PFMigration Synced 246428       1
PFMailbox43 PFMigration Synced 101837       0
PFMailbox45 PFMigration Synced 157571       0
PFMailbox44 PFMigration Synced 61763        0
PFMailbox40 PFMigration Synced 70637        1
PFMailbox41 PFMigration Synced 143042       0
PFMailbox42 PFMigration Synced 81254        0
PFMailbox39 PFMigration Synced 68876        2
PFMailbox15 PFMigration Synced 58221        0
PFMailbox27 PFMigration Synced 28065        0
PFMailbox24 PFMigration Synced 31869        1
PFMailbox5  PFMigration Synced 64125        0
PFMailbox30 PFMigration Synced 72938        1
PFMailbox33 PFMigration Synced 32545        1
PFMailbox31 PFMigration Synced 93782        0
PFMailbox32 PFMigration Synced 28743        0
PFMailbox25 PFMigration Synced 100794       0
PFMailbox26 PFMigration Synced 35412        0
PFMailbox28 PFMigration Synced 27003        0
PFMailbox29 PFMigration Synced 80510        0
PFMailbox17 PFMigration Synced 97952        1
PFMailbox8  PFMigration Synced 18601        0
PFMailbox34 PFMigration Synced 87150        0
PFMailbox35 PFMigration Synced 31531        0
PFMailbox36 PFMigration Synced 37979        0
PFMailbox37 PFMigration Synced 95770        0
PFMailbox10 PFMigration Synced 14193        0
PFMailbox16 PFMigration Synced 64323        1

Enjoy (modern) public folders.



  • 2016-12-20: Public folder migration batch example added

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