We often get questions like "Where is my Microsoft Outlook data stored?" "Where are my contact?" "How do I backup my calendar?"

Everything, your mail, calendar, and contacts in your Outlook folders are either in a mailbox on an Exchange Server or in Personal Folders .pst files on your computer.

Backup and dual-booting between Windows versions all involve using the same files. There is no backup process built into Outlook. To back up, simply exit Outlook, then copy the files you want to back up. Below we provide a chart of Outlook file locations, followed by notes on particular files. Note that unlike older versions of Outlook, many configuration files are stored in the mailbox or PST.

If you are want to copy back and forth between machines so you can use the same information at the office and at home, for example. you'll need to copy at least the pst file. If you have Outlook profiles, name them the same on both machines, so you can use the same files easily. Use File tab | Account Settings to open the pst files that you copied.

See Moving Microsoft Outlook to a New Computer for the steps needed to move Outlook files to a new computer.

See How to move the IMAP personal folder (*.pst) for the proper way to move IMAP and Internet Subscription folders.

If you dual-boot, your profile can point to the same .pst and .ost files (stored in a location both OS's can see), but you would need to copy other files to the correct location on the second operating system. Note that if you dual boot, you should use the same version of Outlook on both partitions for best results.

Windows XP File Locations | Vista & Win7 File Locations | Personal Folders Files
Offline Folders File | Personal Address Book | Other Files | Accounts
Microsoft Personal Folders Backup Utility | Tools | Notes | More Information

Windows 7/8/10 File Locations

Where do you find these files? You can always start by using your operating system's Search or Find command to locate the particular file types. On Vista you may need to browse to Windows Explorer's Organize | Folder and Search Options | View tab and select Show hidden files and folders.

As of Outlook 2010, Personal Folders Files (*.pst) are in the Outlook Files folder in your My Documents folder.

Beginning with Vista, Windows replaces Documents and Settings folder path with a Users path. As a result, you'll find Outlook stores the *.ost, *.oab, and extend.dat, in C:\Users\%username%\AppData\Local\Microsoft\Outlook.

POP3 and Exchange offline or cache storage can be moved to other locations. See How to move the IMAP personal folder (*.pst) for the proper way to move IMAP and Internet Subscription folders.

All other Outlook configuration files are stored in C:\Users\%username%\AppData\Roaming\Microsoft\Outlook and cannot be moved.

Note: Storing Personal Folders on an network file share is not recommended and may cause corruption and data loss.

Windows XP File Locations

Where do you find these files? You can always start by using your operating system's Search or Find command to locate the particular file types. You may need to use Tools | Folder Options | View in Windows Explorer and select Show hidden files and folders.
New to Outlook 2010, Personal Folders Files (*.pst) are in the Outlook Files folder in your My Documents folder.
When using Windows XP, Outlook stores *.ost, *.oab, and extend.dat in
C:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook
Extend.dat and MSN Connector message stores can not be moved. See How to move the IMAP personal folder (*.pst) for the proper way to move IMAP and Internet Subscription folders.

All other Outlook configuration files are stored in C:\Documents and Settings\username\Application Data\Microsoft\Outlook and cannot be moved.

Note: Storing Personal Folders on an network file share is not recommended and may cause corruption and data loss.

Personal Folders Files

If you are not connecting to Microsoft Exchange Server, all your Microsoft Outlook data is stored in one or more Personal Folders (.pst) files.

Outlook 2010 creates new *.pst files in your My Documents folder, in a folder named Outlook Files. This will make it easier for you to backup your mail.

If you upgraded from an older version and did not make a new profile or pointed the new profile to the old *.pst files, check the properties for Personal Folders in File tab | Account Settings | Data Files tab to determine the exact location on your system.

Some people like to export a folder, such as Contacts, to a separate backup .pst file. That's fine for the data, but it does not back up any folder customizations such as views and custom forms. If you want to back up those, too, copy the entire folder to a new .pst file instead of using the export feature.

Also see:

• Why .pst Files Are Unsupported Over a LAN or WAN Link

Offline Folders File

If you use Microsoft Exchange Server, you may have an offline or cache mode folders (.ost) file. You shouldn't need to back it up, since you can always refresh it by synchronizing with the server. However, be sure you understand the procedure for Convert an Exchange Offline file (OST) to a Personal Folders file (PST). If something ever goes wrong with your Exchange Server mailbox, this technique can save time and information, but you must do it before you try to connect to the server again.

Ribbon and QAT

Beginning with Outlook 2010, the ribbon is customizable and it and the quick access toolbar (QAT) can be exported from the Outlook interface (File, Options, Customize Ribbon), either to share with other computers or users or as a backup.

The ribbon and QATcustomizations are stored in olk*.officeUI files at C:\Users\username\AppData\Local\Microsoft\Office. Each Outlook item type that has a customized ribbon will have an office.UI file.

Personal Address Book

Most Outlook users no longer use a PAB because the Personal Address Book (.pab file) is deprecated. If you still have a PAB, the contents need be imported into your Contacts folder. The *.pab will not open in Outlook 2010.

To Import the *.pab, go to File Tab | Open | Import. Choose Import from another program or file, then scroll down and choose Personal Address Book.

Other Files

Outlprnt file contains your custom print settings. This does not need to be backed up.

Some other miscellaneous files, not necessarily worth backing up:

• Extend.dat -- Information about installed add-ins. Will be recreated if you delete it.
• Outitems.log -- Outlook items to be placed automatically in the Journal
• Offitems.log -- Office items to be placed automatically in the Journal
• Frmcache.dat -- Outlook forms cache file. See How the Microsoft Outlook forms cache works.

Accounts

Account information is held in the user's Windows registry, not in a file, at HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles

While you could export this key, its not generally recommended because it contains absolute paths to files (in your user account folders) and information about installed add-ins. If the path is not exact when you restore it the profile will be corrupt.

If you want to back the key up so you can restore the profile to the same computer, you can use a command line to export the key (use a valid path for the exported file). Note: this command is all one line:

regedit /e C:\Users\username\Documents\outlook.reg HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles

Using the Microsoft Personal Folders Backup Utility

In order to use the Microsoft Personal Folder Backup utility with Outlook 2010, you need to add the following key to your Registry. This changes the shutdown behavior of Outlook 2010 back to the shutdown behavior of Outlook 2007 SP2.

HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\Microsoft.OutlookBackup.1
DWORD: RequireShutdownNotification
Value: 1

Ready to use reg file: RequireShutdownNotification

How to enable Personal Folders Backup add-in to work with Outlook 2010 (MSKB)

Notes

If your network is set up so that you can use Outlook at any machine ("roaming profiles"), your Outlook files may be in a different location. Try using Start | Find to locate each type of file. If you don't see any .pst files after you search, you may need to adjust the settings in Windows Explorer to show hidden and system files. Choose Tools | Folder Options, then switch to the View tab, and select Show hidden files and folders.

Personal Folders .pst files are among the files that are normally not included in a Windows 2000 (or later) offline files synchronization. However, you can edit the system policy that controls the file types so that .pst files can be included. See Error Message Files of This Type Cannot Be Made Available Offline.