Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-04-10

This topic discusses where clients specific to Microsoft Exchange Server 2007 store configuration and end-user data. When you are making a disaster recovery plan, you should understand the backup and restore methods available for this data.

Where Clients Store Configuration and End-User Data

Table 1 outlines where clients store configuration and end-user data. It also indicates the backup and restore methods that you should use for each type of data.

Table 1   Locations used by clients for configuration and end user data

Critical data Location Backup method Restore method

.pst files where Microsoft Outlook stores locally saved end user data

File system (varies depending upon client settings)

File-level backup

File-level restore

.ost files where Outlook stores locally saved end user data

File system (varies depending upon client settings)

File-level backup

File-level restore

Microsoft Office Outlook custom configuration files where Outlook stores local end user client customizations

File system (varies depending upon client settings)

File-level backup

File-level restore

Messaging Application Programming Interface (MAPI) profiles

Microsoft Windows registry:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft \Exchange 

  • HKLM\SYSTEM\CurrentControlSet\Services

System state backup or registry export

System state restore or registry import

POP3 and IMAP4 clients

File system (location depends on the client software and in what format the end-user data is stored)

File-level backup

File-level restore

Outlook .pst Files

The .pst file is a storage file for Outlook information that does not require an Exchange server. Unlike the .ost file, the .pst file is not synchronized with the server, and it is not associated with a mailbox. A .pst file can be accessed with a MAPI application. A .pst file can be used in the following ways:

  • By Outlook to store mailbox data.

  • As a common e-mail data exchange format. Many commercial e-mail clients are able to import from and export to a .pst file.

The .pst file is a non-synchronized storage file. Losing a .pst file frequently means losing data because the .pst file might contain the only copy of that data. In the event of corruption, you can use the Inbox Repair Tool (Scanpst.exe) to try to repair a .pst file. The tool comes with Outlook. For more information about the Inbox Repair Tool, see Microsoft Knowledge Base article 287497, How to use the Inbox Repair Tools to recover e-mail messages in Outlook 2002 and Outlook 2003.

Outlook .ost Files

The .ost file is an offline copy of all the end-user data that exists on a user's mailbox on an Exchange server. The .ost file is created when Outlook is running in cached mode and associated with a specific mailbox. The .ost file can be used for the following:

  • A mobile user can use an .ost file to work with an offline copy of e-mail while disconnected from the network.

  • An .ost file is used by Office Outlook 2007 and Outlook 2003 to reduce the number of MAPI calls from the client to a server that is running Exchange.

The .ost file is a synchronized copy of that data on the server that is running Exchange. Losing the .ost file will only result in a loss of any changes (for example, in Drafts or Outbox) that have not been synchronized with the server. Remote users are at the most risk of losing data in this manner because they can be offline for extended periods of time. The .ost file can be re-created by synchronizing all the data on the server that is running Exchange.

Outlook Custom Configurations

In addition to the Exchange-related data that Outlook stores in the .pst and .ost files, Outlook also stores other client specific configuration data. Most recognizable to end users are the .nk2, or nickname, files. (In Outlook 2000, the file extension is .nick.) The nickname feature, also referred to as AutoNameCheck, works differently in the different versions of Outlook. Its basic function is to automatically complete addresses as they are typed in the To, Cc, or Bcc fields of an e-mail message. For more details about how to back up the nickname files and other Outlook-specific configuration data, see the following topic that relates to the version of Outlook that you are working with:

MAPI Profiles

MAPI refers both to the Messaging Application Programming Interface as well as the proprietary protocol used by Outlook to communicate with Exchange servers. Your MAPI profile contains your client connection information. Losing a MAPI profile is not a major issue. Most clients can re-create their MAPI profiles by using Exchange 2007 Autodiscover. For more information about Autodiscover, see Managing the Autodiscover Service.

POP3 and IMAP4 Clients

There are many POP3 and IMAP4 clients available. To fully understand how to protect data on these clients, consult the documentation that came with that software.