Exchange cleanup improvements (#3551)

Exchange cleanup improvements:
* Explicitly clean-up folders in DeletedItems - Empty folder does not seem to work reliably
* Cleanup any folders in DeletedItems - helps get rid of random manual deletions 
* Harden paging - issues where if no items were deleted initial page, we'd never make progress 
* More focused search on `msgfolderroot`
---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [x] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/cmd/purge/scripts/exchangePurge.ps1

@@ -185,38 +185,62 @@ function Get-FoldersToPurge {
         [string[]]$FolderNamePurgeList = @(),
 
         [Parameter(Mandatory = $False, HelpMessage = "Purge folders with these prefixes")]
-        [string[]]$FolderPrefixPurgeList = @()
+        [string[]]$FolderPrefixPurgeList = @(),
+
+        [Parameter(Mandatory = $False, HelpMessage = "Perform shallow traversal only")]
+        [bool]$PurgeTraversalShallow = $false
     )
 
-    $foldersToDelete = @()
+    Write-Host "`nLooking for folders under well-known folder: $WellKnownRoot matching folders: $FolderNamePurgeList or prefixes: $FolderPrefixPurgeList for user: $User"
     
+    $foldersToDelete = @()
+    $traversal = "Deep"
+    if ($PurgeTraversalShallow) {
+        $traversal = "Shallow"
+    }
+
+    $offset = 0
+    $moreToList = $true
+
+    # get all folder pages
+    while ($moreToList) {
         # SOAP message for getting the folders
         $body = @"
-<FindFolder Traversal="Deep" xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
+<FindFolder Traversal="$traversal" xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
     <FolderShape>
         <t:BaseShape>Default</t:BaseShape>
         <t:AdditionalProperties>
             <t:ExtendedFieldURI PropertyTag="0x3007" PropertyType="SystemTime"/>
         </t:AdditionalProperties>
     </FolderShape>
+    <m:IndexedPageFolderView MaxEntriesReturned="1000" Offset="$offset" BasePoint="Beginning" />
     <ParentFolderIds>
         <t:DistinguishedFolderId Id="$WellKnownRoot"/>
     </ParentFolderIds>
 </FindFolder>
 "@
 
-    Write-Host "`nLooking for folders under well-known folder: $WellKnownRoot matching folders: $FolderNamePurgeList or prefixes: $FolderPrefixPurgeList for user: $User"
+        try {
+            Write-Host "`nRetrieving folders starting from offset: $offset"
+
             $getFolderIdMsg = Initialize-SOAPMessage -User $User -Body $body
             $response = Invoke-SOAPRequest -Token $Token -Message $getFolderIdMsg
 
-    # Get the folders from the response
-    $folders = $response | Select-Xml -XPath "//t:Folders/*" -Namespace @{t = "http://schemas.microsoft.com/exchange/services/2006/types" } | 
-    Select-Object -ExpandProperty Node
-
             # Are there more folders to list
             $rootFolder = $response | Select-Xml -XPath "//m:RootFolder" -Namespace @{m = "http://schemas.microsoft.com/exchange/services/2006/messages" } | 
             Select-Object -ExpandProperty Node
             $moreToList = ![System.Convert]::ToBoolean($rootFolder.IncludesLastItemInRange)
+        }
+        catch {
+            Write-Host "Error retrieving folders"
+
+            Write-Host $response.OuterXml
+            Exit
+        }
+    
+        # Get the folders from the response
+        $folders = $response | Select-Xml -XPath "//t:Folders/*" -Namespace @{t = "http://schemas.microsoft.com/exchange/services/2006/types" } | 
+        Select-Object -ExpandProperty Node
 
         # Loop through folders
         foreach ($folder in $folders) {
@@ -254,8 +278,16 @@ function Get-FoldersToPurge {
             }
         }
 
+        if (!$moreToList -or $null -eq $folders) {
+            Write-Host "Retrieved all folders."
+        }
+        else {
+            $offset += $folders.count
+        }
+    }
+
     # powershel does not do well when returning empty arrays
-    return $foldersToDelete, $moreToList
+    return , $foldersToDelete
 }
 
 function Empty-Folder {
@@ -355,7 +387,10 @@ function Purge-Folders {
         [string[]]$FolderPrefixPurgeList = @(),
 
         [Parameter(Mandatory = $False, HelpMessage = "Purge folders before this date time (UTC)")]
-        [datetime]$PurgeBeforeTimestamp
+        [datetime]$PurgeBeforeTimestamp,
+
+        [Parameter(Mandatory = $False, HelpMessage = "Perform shallow traversal only")]
+        [bool]$PurgeTraversalShallow = $false
     )  
 
     if (($FolderNamePurgeList.count -eq 0) -and 
@@ -364,9 +399,6 @@ function Purge-Folders {
         Exit
     }
 
-    Write-Host "`nPurging CI-produced folders..."
-    Write-Host "--------------------------------"
-
     if ($FolderNamePurgeList.count -gt 0) {
         Write-Host "Folders with names: $FolderNamePurgeList"
     }
@@ -382,20 +414,18 @@ function Purge-Folders {
         'WellKnownRoot'         = $WellKnownRoot;
         'FolderNamePurgeList'   = $FolderNamePurgeList;
         'FolderPrefixPurgeList' = $FolderPrefixPurgeList;
-        'PurgeBeforeTimestamp'  = $PurgeBeforeTimestamp
+        'PurgeBeforeTimestamp'  = $PurgeBeforeTimestamp;
+        'PurgeTraversalShallow' = $PurgeTraversalShallow
     }
 
-    $moreToList = $True
+    $foldersToDelete = Get-FoldersToPurge @foldersToDeleteParams
-    # only get max of 1000 results so we may need to iterate over eligible folders  
-    while ($moreToList) {
-        $foldersToDelete, $moreToList = Get-FoldersToPurge @foldersToDeleteParams
     $foldersToDeleteCount = $foldersToDelete.count
     $foldersToDeleteIds = @()
     $folderNames = @()
 
     if ($foldersToDeleteCount -eq 0) {
         Write-Host "`nNo folders to purge matching the criteria"
-            break
+        return
     }
 
     foreach ($folder in $foldersToDelete) {
@@ -405,7 +435,6 @@ function Purge-Folders {
      
     Empty-Folder -FolderIdList $foldersToDeleteIds -FolderNameList $folderNames
     Delete-Folder -FolderIdList $foldersToDeleteIds -FolderNameList $folderNames
-    }
 }
 
 function Create-Contact {
@@ -459,7 +488,7 @@ function Get-ItemsToPurge {
     $foldersToSearchBody = "<t:DistinguishedFolderId Id='$WellKnownRoot'/>"
 
     if (![String]::IsNullOrEmpty($SubFolderName)) {
-        $subFolders, $moreToList = Get-FoldersToPurge -WellKnownRoot $WellKnownRoot -FolderNamePurgeList $SubFolderName -PurgeBeforeTimestamp $PurgeBeforeTimestamp
+        $subFolders = Get-FoldersToPurge -WellKnownRoot $WellKnownRoot -FolderNamePurgeList $SubFolderName -PurgeBeforeTimestamp $PurgeBeforeTimestamp
 
         if ($subFolders.count -gt 0 ) {
             $foldersToSearchBody = ""
@@ -615,6 +644,8 @@ function Purge-Items {
     }
 }
 
+### MAIN ####
+
 Write-Host 'Authenticating with Exchange Web Services ...'
 $global:Token = Get-AccessToken | ConvertTo-SecureString -AsPlainText -Force 
 
@@ -622,14 +653,17 @@ $global:Token = Get-AccessToken | ConvertTo-SecureString -AsPlainText -Force
 $FolderNamePurgeList = $FolderNamePurgeList | ForEach-Object { @($_.Split(',').Trim()) }
 $FolderPrefixPurgeList = $FolderPrefixPurgeList | ForEach-Object { @($_.Split(',').Trim()) }
 
+Write-Host "`nPurging CI-produced folders under 'msgfolderroot' ..."
+Write-Host "--------------------------------------------------------"
+
 $purgeFolderParams = @{
-    'WellKnownRoot'         = "root";
+    'WellKnownRoot'         = "msgfolderroot";
     'FolderNamePurgeList'   = $FolderNamePurgeList;
     'FolderPrefixPurgeList' = $FolderPrefixPurgeList;
     'PurgeBeforeTimestamp'  = $PurgeBeforeTimestamp
 }
 
-#purge older prefix folders
+#purge older prefix folders from msgfolderroot
 Purge-Folders @purgeFolderParams
 
 #purge older contacts 
@@ -647,4 +681,20 @@ Purge-Items -ItemsFolder "calendar" -ItemsSubFolder "Birthdays" -PurgeBeforeTime
 # -/Recoverable Items/SubstrateHolds
 Write-Host "`nProcess well-known folders that are always purged" 
 Write-Host "---------------------------------------------------" 
-Empty-Folder -WellKnownRoot "deleteditems", "recoverableitemsroot"
+
+# We explicitly also clean direct folders under Deleted Items since there is some evidence
+# that suggests that emptying alone may not be reliable
+Write-Host "`nExplicit delete of all folders under 'DeletedItems' ..."
+Write-Host "----------------------------------------------------------"
+
+$purgeFolderParams = @{
+    'WellKnownRoot'         = "deleteditems";
+    'FolderNamePurgeList'   = $FolderNamePurgeList;
+    'FolderPrefixPurgeList' = @('*');
+    'PurgeBeforeTimestamp'  = (Get-Date);
+    'PurgeTraversalShallow' = $true
+}
+
+Purge-Folders @purgeFolderParams
+
+Empty-Folder -WellKnownRootList "deleteditems", "recoverableitemsroot"