New Features in Exchange Server 2016 CU6 (Part 2 of 2)

This is part 2 of the article.  See part 1 here

Original Folder Item Recovery

In older versions of Exchange Server, like Exchange 2003 and 2007, there was a feature called Dumpster (or Dumpster 1.0), that allowed restoring deleted items. It worked in the following way:

When a user removes an item, it remains in the same folder, but the deleted object becomes stamped with ptagDeletedOnFlag. Items tagged with this flag become invisible and cannot be searched or indexed. If a user needed to restore a deleted message, they could use the Recover Deleted Items view to find it and perform the restore. They could also purge the message from this view as well.

When Exchange 2010 was released, there was a new feature called “litigation hold” that allowed keeping mailbox items in an unaltered state. Organizations could preserve all messages related to a specific topic or stored in a certain mailbox. The purpose of litigation hold was to comply with legal hold requirements, which state that messages placed on hold must be searchable and cannot be purged. This was one of the reasons that the dumpster became unavailable in Exchange Server 2010.

Instead, Exchange 2010 has a feature called the “Recoverable Items Folder”. This folder is hidden from the normal view of email clients such as Outlook and OWA. The recoverable items folder works the following way:

When a user hard deletes a message (shift + delete) or remove sthe message from the Deleted Items folder, it doesn’t stay in the same folder like it did with Exchange 2007.  It goes to the Recoverable Items Folder, where it’s stored until the deleted items retention period is expired. The Recoverable Items Folder contains four separate subfolders:

  • Deletions. This subfolder contains all items emptied from the Deleted Items folder or hard-deleted. Users can restore messages from this subfolder using the Recover Deleted Items feature in Outlook and OWA.
  • Versions.  This subfolder contains the original and modified copies of the items under litigation hold. For example, if a user is placed on litigation hold and changes any message in their mailbox – the copy of the original item will be stored in the Versions subfolder.
  • Purges.  This subfolder contains items that were purged from the Deletions subfolder and items that have exceed the deleted item retention period configured on the mailbox database. When the Mailbox Folder Assistant processes the mailbox, it removes the contents of this subfolder completely (or doesn’t, if the mailbox has been placed on litigation hold).
  • Audits.  If audit logging is enabled for a mailbox, this subfolder contains the audit log entries.


As you can see, the Recoverable Items Folder has considerable advantages over the old-style Dumpster. However, it did have one disadvantage – when you restored an item, it didn’t go to the original folder, it just moved the item to the Deleted Items folder in the visible portion of the user’s mailbox. Now, with Exchange 2016 CU6, the “Original Folder Item Recovery” feature allows recovering an item back to the original folder.

It works by using the LastActiveParentEntryID MAPI property (ID 348A). When an item is deleted (either hard- or soft-), this value is stamped on the message or item.  If you attempt a recovery action, the value of this stamp is read and used as the move destination endpoint.

Unfortunately, this feature currently only in Outlook on the Web, and isn’t supported for Microsoft Office Outlook (it’s possible Outlook will support this feature in a future update).

Both Sent Items Behavior Control & Original Folder Item Recovery are new features designed to improve user experience and reduce the administrative effort for Exchange administrators.

As we can see, even though Microsoft actively promotes Office 365, on-premises Exchange get new features too.




Marat Mussabekov

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