Understanding Recoverable Items

Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

To protect from accidental or malicious deletion and to facilitate discovery efforts commonly undertaken before or during litigation or investigations, Microsoft Exchange Server 2010 introduces the Recoverable Items folder. The Recoverable Items folder replaces the feature known as the dumpster in Exchange Server 2007. The Recoverable Items folder is used by the following Exchange features:

• Deleted item retention

• Single item recovery

• Litigation hold

• Mailbox audit logging

Contents

Terminology

Recoverable Items Folder

Recoverable Items Mailbox Quotas

Terminology

Knowledge of the following terms will help you understand the content in this topic.

• Delete
  Describes when an item is deleted from any folder and placed in the Deleted Items default folder.

• Soft delete
  Describes when an item is deleted from the Deleted Items default folder and placed in the Recoverable Items folder. Additionally describes when a Microsoft Outlook user deletes an item by pressing Shift+Delete, which bypasses the Deleted Items folder and places the item directly in the Recoverable Items folder.

• Hard delete
  Describes when an item is marked to be purged from the mailbox database. This is also known as a store hard delete.

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Recoverable Items Folder

To better meet customers' legal compliance requirements, the dumpster is reinvented as the Recoverable Items folder in Exchange 2010. The Recoverable Items folder resides in the non-IPM subtree of each mailbox. The non-IPM subtree is a storage area within the mailbox that contains operational data about the mailbox. This subtree isn't visible to users using Outlook, Microsoft Office Outlook Web App, or other e-mail clients.

This architectural change provides the following key benefits:

• When a mailbox is moved to another mailbox database, the Recoverable Items folder moves with it.

• The Recoverable Items folder is indexed by Exchange Search and can be discovered using Multi-Mailbox Search.

• The Recoverable Items folder has its own storage quota.

• Exchange can prevent data from being purged from the Recoverable Items folder.

• Exchange can track edits of certain content.

The Recoverable Items folder contains the following subfolders:

• Deletions   This subfolder contains all items deleted from the Deleted Items folder. (In Outlook, you can soft delete an item by pressing Shift+Delete.) This subfolder is exposed to users through the Recover Deleted Items feature in Outlook and Outlook Web App.

• Versions   If either litigation hold or single item recovery is enabled, this subfolder contains the original and modified copies of the deleted items. This folder isn't visible to end users.

• Purges   If either litigation hold or single item recovery is enabled, this subfolder contains all items that are hard deleted. This folder isn't visible to end users.

• Audits   If mailbox audit logging is enabled for a mailbox, this subfolder contains the audit log entries. To learn more about mailbox audit logging, see Understanding Mailbox Audit Logging.

Deleted Item Retention

An item is considered to be soft deleted in the following cases:

• A user deletes an item or empties all items from the Deleted Items folder.

• A user presses Shift+Delete to delete an item from any other mailbox folder.

Soft-deleted items are moved to the Deletions subfolder of the Recoverable Items folder. This provides an additional layer of protection so users can recover deleted items without requiring Help desk intervention. Users can use the Recover Deleted Items feature in Outlook or Outlook Web App to recover a deleted item. Users can also use this feature to permanently delete an item.

Items remain in the Deletions subfolder until the deleted item retention period is reached. The default deleted item retention period for a mailbox database is 14 days. You can modify this period for a mailbox database or for a specific mailbox. In addition to a deleted item retention period, the Recoverable Items folder is also subject to quotas. To learn more, see Recoverable Items Mailbox Quotas later in this topic.

After the deleted item retention period elapses, the item is moved to the Purges folder and is no longer visible to the user. When the Managed Folder Assistant processes the mailbox, items in the Purges subfolder are purged from the mailbox database.

Single Item Recovery

If an item is removed from the Deletions subfolder, either using the Recover Deleted Items feature or by an automated process such as the Managed Folder Assistant, the item can't be recovered by the user. In previous versions of Exchange, recovering these items required the administrator to restore the mailbox database or a mailbox from backup copies. This process generally delayed recovery by minutes or hours, depending on the backup mechanism used.

Exchange 2010 introduces single item recovery, a feature you can use to recover items without having to restore the mailbox databases using backup media. This results in considerably shorter recovery periods. When the Managed Folder Assistant processes the Recoverable Items folder for a mailbox that has single item recovery enabled, any item in the Purges subfolder isn't purged if the deleted item retention period hasn't elapsed for that item. Additionally, if the user changes certain properties of an item in any mailbox folder, a copy of the item is made before the modification is written to the Exchange store. The copy is stored in the Versions subfolder by a process known as copy-on-write page protection. You can recover different versions of a modified item until the deleted item retention period elapses.

The following table lists the contents of and actions that can be performed in the Recoverable Items folder if single item recovery is enabled.

Recoverable Items folder and single item recovery

Single item recovery isn't enabled by default for new mailboxes or mailboxes moved from a previous version of Exchange. You must use the Exchange Management Shell to enable single item recovery for a mailbox, and then configure or modify the deleted item retention period. To learn more about how to enable single item recovery for a mailbox and to perform single item recovery of deleted items, see the following topics:

• Enable Single Item Recovery for a Mailbox

• Perform Single Item Recovery

Litigation Hold

Exchange 2010 introduces Multi-Mailbox Search, a feature that administrators or records managers can use with delegated Discovery Management permissions to perform discovery searches of mailbox content. Exchange 2010 also introduces litigation hold, which you can use to preserve items in user mailboxes and protect the items from deletion by users or automated processes.

Placing a mailbox on litigation hold stops the Managed Folder Assistant from automatically purging messages from the Purges subfolder. Additionally, copy-on-write page protection is also enabled for the mailbox. Copy-on-write page protection creates a copy of the original item before any modifications are written to the Exchange store. After the mailbox is removed from litigation hold, the Managed Folder Assistant resumes automated purging.

The following table lists the contents of and actions that can be performed in the Recoverable Items folder if litigation hold is enabled.

Recoverable Items folder and litigation hold

To learn more about Multi-Mailbox Search and litigation hold, see the following topics:

• Understanding Multi-Mailbox Search

• Understanding Litigation Hold

Copy-on-Write Page Protection and Modified Items

If a user who is placed on litigation hold (or has single item recovery enabled) modifies specific properties of a mailbox item, a copy of the original mailbox item is created before the changed item is written. The original copy is saved in the Versions subfolder. This process is known as copy-on-write page protection. Copy-on-write page protection applies to items residing in any mailbox folder. The Versions subfolder isn't visible to users.

The following table lists the message properties that trigger copy-on-write page protection.

Properties that trigger copy-on-write page protection

When litigation hold is removed from a mailbox and single item recovery is disabled, copies of modified items stored in the Versions folder are removed.

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Recoverable Items Mailbox Quotas

When an item is moved to the Recoverable Items folder, its size is deducted from the mailbox quota and added to the size of the Recoverable Items folder. In Exchange 2010, mailbox databases have a configurable Recoverable Items warning quota (soft limit) of 20 gigabytes (GB) and a Recoverable Items quota (hard limit) of 30 GB. By default, these limits are inherited by all mailboxes in the database. However, you can configure individual mailboxes with different quotas. To learn more, see Configure Deleted Item Retention and Recoverable Items Quotas.

When the Recoverable Items folder for a mailbox reaches the Recoverable Items quota, no more items can be stored in the folder. This impacts mailbox functionality in the following ways:

• Mailbox users can't delete items.

• The Managed Folder Assistant can't delete items based on retention tag or managed folder settings.

• For mailboxes that have single item recovery or litigation hold enabled, the copy-on-write page protection process can't maintain versions of items edited by the user.

• For mailboxes that have mailbox audit logging enabled, no mailbox audit log entries can be saved in the Audits subfolder.

For mailboxes that aren't placed on litigation hold, the Managed Folder Assistant automatically purges items from the Recoverable Items folder when the deleted item retention period elapses. If the folder reaches the Recoverable Items warning quota, the assistant automatically purges items in FIFO order.

When the Recoverable Items folder reaches the soft and hard limit defaults, you are notified by means of an event log and a Microsoft System Center Operations Manager alert. This alert fires when the Recoverable Items folder first reaches the soft and hard limit defaults, and then once daily afterward.

The following table lists the events logged when the Recoverable Items folder reaches the soft and hard limit defaults.

Recoverable Items quota warnings and errors

If the mailbox is placed on litigation hold, copy-on-write page protection can't maintain versions of modified items. To maintain versions of modified items, you must reduce the size of the Recoverable Items folder. You can use the Search-Mailbox cmdlet to copy messages from the Recoverable Items folder of a mailbox to a discovery mailbox, and then delete the items from the mailbox. Alternatively, you can also raise the Recoverable Items quota for the mailbox. For details, see Clean Up the Recoverable Items Folder.

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