Understanding Personal Archives

You can use personal archives to regain control of the organization's messaging data by eliminating the need for personal store (.pst) files and allow users to store messages in an archive mailbox that's accessible in Microsoft Outlook 2010 and Microsoft Office Outlook Web App.

Messaging Data and .pst Files

Outlook uses .pst files to store data locally on users' computers or network shares. Unlike offline store (.ost) files used by Outlook to store a copy of the mailbox for offline access, .pst files aren't synchronized with the user's Exchange mailbox. Users can move messages to a .pst file, resulting in the moved messages being removed from the mailbox.

Some management challenges when using .pst files include:

  • Unmanaged files   Generally, .pst files are created by users and reside on their computers or network shares. They aren't managed by your organization. Users can create a number of .pst files containing the same or different messages and store them in different locations, with no organizational control.
  • Increased discovery costs   When discovery requests as a result of a lawsuit or other business or regulatory requirements occur, locating messaging data that resides in .pst files on users' computers can be a costly manual effort. Because tracking unmanaged .pst files can be difficult, .pst data may be undiscoverable in many cases. This could possibly expose your organization to legal and financial risks.
  • Inability to apply messaging retention policies   Messaging retention policies can't be applied to messages located in .pst files. As a result, depending on business or applicable regulations, your organization may not be in compliance.
  • Risk of data theft   Messaging data that's stored in .pst files is vulnerable to data theft. For example, .pst files are often stored in portable devices such as laptops, removable hard drives, and portable media such as USB drives, CDs, and DVDs.
  • Fragmented view of messaging data   Users who store information in .pst files don't get a uniform view of their data. Messages stored in .pst files are generally available on the computer where the .pst file resides. When accessing a mailbox using Outlook Web App or using Outlook on another computer, messages stored in .pst files are inaccessible.

Personal Archives

In Microsoft Exchange Server 2010, you can use personal archives to provide users with an alternate storage location in which to store historical messaging data. With this functionality, Outlook 2010 and Outlook Web App users have seamless access to their archive mailbox. Using either of these client applications, users can view an archive mailbox and move or copy messages between their primary mailbox and the archive. Personal archives present a consistent view of messaging data to users and eliminate the user overhead required to manage .pst files. Eliminating the use of .pst files significantly reduces your organization's exposure to the risks outlined in the previous section.

Creating and managing archive mailboxes is integrated with common mailbox management tasks. When creating a primary user mailbox, you can also create an archive mailbox, or you can enable an archive mailbox for existing mailboxes. You can also easily disable or remove an archive mailbox. A user's archive mailbox resides on the same mailbox database as the user's primary mailbox. When moving the user's primary mailbox from one mailbox database to another, the archive mailbox is moved along with the primary mailbox.

For details about how to manage archive mailboxes, see Managing Personal Archive.

"Move to Archive" Policies

In Exchange 2010, you can apply archive policies to a mailbox that will automatically move messages from a user's primary mailbox to the archive mailbox after a specified period. Messages are retained in the archive mailbox until they are removed by the user. Archive policies are retention policies implemented by creating retention tags that specify the Move to archive action.


You can't apply a managed folder mailbox policy to mailboxes that have a personal archive. Managed content settings created for managed folders can't use the Move to archive action.

To learn more about retention policies, retention tags, and the Move to archive retention action, see Understanding Retention Tags and Retention Policies.

Default Archive Policy

Exchange Server Setup creates a default archive policy. The default archive policy is a retention policy that contains the following retention tags.

Retention tag name Tag type Description

Default 2 year move to archive


Messages are automatically moved to the archive mailbox after 2 years. Applies to items in the entire mailbox that don't have a retention tag applied explicitly or inherited from the folder.

Personal 1 year move to archive


Messages are automatically moved to the archive mailbox after 365 days.

Personal 5 year move to archive


Messages are automatically moved to the archive mailbox after five years.

Personal never move to archive


Messages are never moved to the archive mailbox.

When you enable a personal archive for a mailbox, the archive is automatically assigned the default archive policy. After the Microsoft Exchange Mailbox Assistants service processes the mailbox, these tags become available to the user, who can then tag folders or messages to be moved to the archive mailbox. By default, e-mail messages from the entire mailbox are moved after two years.


When you apply a retention policy to users who have an archive mailbox, the retention policy replaces the default archive policy. You can create one or more retention tags with the Move to archive action and then link the tags to the retention policy. You can also add the default Move to archive tags linked to the default archive policy to any retention policies you create.
Retention tags linked to the default archive policy are system tags created by Exchange 2010 Setup. By default, system tags aren't returned in the list of retention tags when you run the Get-RetentionPolicyTag cmdlet. To return a list of system tags, you must use the IncludeSystemTags switch. You should never delete system tags.

Archive Quotas

Archive mailboxes are designed to allow users to store historical messaging data outside their primary mailbox. Often, users use .pst files due to low mailbox storage quotas and the restrictions imposed when these quotas are exceeded. For example, users can be prevented from sending messages when their mailbox size exceeds the Prohibit send quota. Similarly, users can be prevented from sending and receiving messages when their mailbox size exceeds the Prohibit send and receive quota.

To eliminate the need for .pst files, it's important that you provide an archive mailbox with storage limits that meet the user's requirements. However, at the same time, you may still want to retain some control the storage quotas and growth of archive mailboxes to help monitor costs and expansion.

To help with this control, you can configure archive mailboxes with an archive warning quota and an archive quota. When an archive mailbox exceeds the specified archive warning quota, an event is logged, and a warning message is sent to the mailbox user. When an archive mailbox exceeds the specified archive quota, messages are no longer moved to the archive, and a warning message is sent to the mailbox user. By default, the archive warning quota and archive quota are set to Unlimited. For details about how to configure these quotas, see Configure Personal Archive Quotas for a Mailbox.