Monday, October 12, 2009

Exchange 2010 Dumpster 2.0

In this post I will be going over Dumpster 1.0 which was around in Exchange 2003 and 2007 and how it worked. I will then be covering Dumpster 2.0 in Exchange 2010 and the differences between the two.

What is the Dumpster?

The dumpster is a location that deleted email go after a user has removed them from their mailbox completely. These deleted emails hang around for a retention period of of x amount of days which is configured by the exchange administrator. This is not the deleted items container in outlook or OWA, it is a special place for emails removed entirely from the outlook interface.

Provided the administrator has a retention period setup in place for deleted items, an end user can use Outlook or OWA to recover items out of the exchange mailbox dumpster by using Recover Deleted Items. If there is no retention set, when emails are deleted from a mailbox they are gone forever.

By default permanently deleted emails are retained for 7 days in 2003 and 14 days in 2007.

Dumpster 1.0

Dumpster 1.0 worked by marking items that are permanently deleted with a ptagDeletedOnFlag flag attribute. Items permanently deleted remain in the place they where deleted. If you were to delete an email from outlook or OWA it would normally go to your deleted items. If you were to then delete it from your deleted items it would be marked with the ptagDeletedOnFlag flag attribute.

One thing to note here, you can delete an item from your inbox or another folder in outlook by using Shift + Delete. This will send it straight to the dumpster bypassing the deleted items folder. When you do this it gets marked with the ptagDeletedOnFlag attribute however by default you cannot use the recovered deleted items option in outlook. Recover Deleted Items only work if the item was permanently deleted when residing in the users deleted items out of the box. See below for Inbox the Recover Deleted Items is greyed out.

However for the Deleted Items container it is fine:

There is a registry key you can set on the workstations to allow users to recover items from the dumpster in any directory called DumpsterAlwaysOn, see Microsoft KB886205. I personally always create a custom ADM to enable this key on everyones workstation for dumpster 1.0. Flick me an email or leave a comment if you would like information on how to do this.

Dumpster 2.0

In Exchange 2010 the Dumpster has been redesigned to perform the following actions:
- Ensure Exchange Dumpster Data moves with the mailbox
- Dumpster data is indexed and discoverable by search
- Dumpster data must have a quota
- Ability to prevent purging data from a users dumpster
- Track editing of certain content (visioning in the dumpster)
- Dumpster should be per mailbox not per folder.

In Dumpster 2.0 it no longer flags emails users permanently delete with the ptagDeletedOnFlag attribute. Instead Dumpster 2.0 moves the emails to a new folder under the Non-IPM subtree in the users mailbox called Recoverable Items (note this section of the mailbox cannot be viewed by any client side mail clients, only using MAPI editing software such as MFCMAPI).

Inside the Recoverable Items folder there are three sub-folders, each with a different purpose which will be explained below:
- Deletions
- Purges
- Versions

The Deletions folder replaces the ptagDeletedOnFlag attribute, now emails are moved from their original location to the Deletions folder. If a user empties their Deleted Items folder or Shift Deletes an email, this is where it goes.

In Dumpster 1.0 users were able to delete items from the Recover Deleted Items folder in result permanently removing them. This allowed users to hide incriminating emails which presented a problem with legality issues and court cases. Now in Dumpster 2.0 if a user deletes an email from the Deletions folder using the recover deleted items tool, it simply moves it to the Purges folder. Once in this folder it cannot be recovered with client side exchange software, however in the case its needed an administrator can use MAPI editing software to pull the email out.

The Versions folder is used for whenever an item has changed, a copy-on-write is performed to preserve the original version of the item into this folder. This folder is not exposed to the end user. Copy on write will capture changes in the subject,t body, attachments, senders/recipients, and sent/received dates. Drafts are exempt from the copy-on-write.

Now with transport dumpster there are two types of modes you can enable:
- Short-term preservation of data
- Long-term preservation of data

Short-term preservation of data

Short-term preservation of data is similar to that of Exchange 2003/2007 just better. This just allows emails to be recovered after a set amount of days after being deleted.

In Exchange 2003/2007 this could only be enabled on a mailbox database level. Now in Exchange 2010 this can be set at a database or mailbox level. If you want to enable retention on a mailbox use:

Set-Mailbox <identity> -SingleItemRecoveryEnabled $true

If you dont run this command on a mailbox you will not be able to set deleted items retention against it on a mailbox leve. To set the retentions in exchange 2010 use the following commands:

Set-MailboxDatabase <identity> -DeletedItemsRetention <number of days>
Set-Mailbox <identity> -DeletedItemsRetention <number of days>

Please note that calendars items maintain the recoverable items folder structure for 120 days in short-term preservation regardless what retention setting you have in place.

Long-term preservation of data

Customers sometimes require mechanisms by which data is maintained for longer periods of time, say indefinitely. This may be required during a litigation hold that occurs when particular users or individuals are involved in undergoing lawsuits. With Exchange 2010 litigation hold can be enabled by using:

Set-Mailbox <identity> -LitigationHoldEnabled $true

Users may go into the the deleted items folder using the recover deleted items tool and delete them, sending them to the purge container. But there they will sit indefinitely with this option set.

Recoverable Items Quotas

Dumpster 2.0 allows you to configure Quota's by using the "RecoverableItemsWarningQuota" or the "RecoverableItemsQuota" policy.

RecoverableItemsWarningQuota provides warnings after the RecoverableItems has exceeded the quota.

RecoverableItemsQuota removes the oldest items in the dumpster to make way for newer items once the quota has been breached.


  1. What happens if you need an individual item recovery from the dumpster as a result of Set-Mailbox - Litigation hold? ie Corruption.

    Does a mapi mailbox level backup and recovery work with Dumpster 2.0... or does it require a wholesale Database recovery.

  2. there are really very few sources of information where u can find something beneficial
    about Rolloff Dumpster n ur post is one of them.

  3. While searching through net I found that your link Rolloff Dumpster gives a information about the dumpster services which is more beneficial for our envirnoment.

  4. What is the difference between Recover Deleted Items Folder and the Transport Dumpster? Are they one and the same? Is the Recover Deleted Items ... pulling from... the Transport Dumpster?