Microsoft Office Outlook 2003 can support much larger Personal Folders (.pst) files than earlier versions--up to 33TB. Given the possibility that archive or export .pst files might grow large enough to crowd out other data on users' hard disks, you might want to look again at .pst file usage in your organization. Outlook 2003 lets you use Group Policy to control the size of both the old and new .pst files. Even if you aren't planning to move to Outlook 2003 any time soon, knowing how Outlook uses .pst files and which uses you can disable in earlier versions can come in handy.

Outlook uses .pst files in more ways than you might realize. The most familiar use is a standalone user using a .pst file instead of an Exchange mailbox as the default information store. Users typically can create additional .pst files by turning on Outlook's AutoArchive feature, which moves older items into a .pst file on a regular schedule, or by using the File, Import and Export command to export data to a .pst file. Outlook also automatically creates a .pst file if the user adds an IMAP4 or Hotmail account to his or her email profile; Outlook uses this .pst file to store a local cache of the IMAP or Hotmail account's messages. Finally, Outlook 2003 creates a new .pst file if the user views a Windows SharePoint Services (WSS) events or contacts list and clicks the "Link to Outlook" link; this .pst file contains the local copy of the linked SharePoint lists.

To provide some control over .pst file use, Outlook 98 and later support a DisablePST registry value. This DWORD value is under the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\11.0\Outlook registry subkey in Outlook 2003; change "11.0" to "10.0" for Outlook 2002, "9.0" for Outlook 2000, or "8.0" for Outlook 98. The DisablePST value isn't present by default, so you need to add it if you want to disable .pst file use. Allowable values are 1 (disabled) and 0 (enabled, the default).

DisablePST's initial use in early builds of Outlook 2002, Outlook 2000, and Outlook 98 was to prevent users from archiving and exporting to or importing from a .pst file. Setting DisablePST to 1 in those versions turns off those features and disables the creation of new .pst files from the File, New menu. User accounts that you configure in Corporate/Workgroup mode, however, can still add a new or existing .pst file to their email profile (through the File, Data File Management dialog box in Outlook 2002 or the Tools, Services dialog box in Outlook 2000 or Outlook 98), so some ad hoc .pst file use is still possible in these versions.

Beginning with Outlook 2002 (with Office XP Service Pack 2--SP2--applied) and continuing with Outlook 2003, DisablePST blocks all user-controlled methods of creating a new .pst file. Setting DisablePST to 1 prevents all new .pst files except those that Outlook itself creates for use with IMAP or Hotmail accounts or WSS lists.

Even with the archive and export features disabled, however, users can open an existing .pst file by using the File, Open, Outlook Data File command, and users can copy or move items into that file. If you want to prevent users from opening a .pst file, you can use Group Policy to disable the Outlook Data File command. You'll need to know the command's ID, which is 5576, and be familiar with Group Policy operations. (For Group Policy resources, search the Windows & .NET Magazine Web site at http://www.winnetmag.com .)

When you deploy Outlook 2003, you can use the Custom Installation Wizard or Custom Maintenance Wizard from the Office Resource Kit (ORK) to determine what kind of .pst files users can create. On the wizards' Change Office User Settings page, look for the PST Settings options under Microsoft Office Outlook 2003/Miscellaneous. You can set values for "Default location for .pst files" and "Preferred PST Mode (Unicode/ANSI)." A Unicode .pst file is the new type supported in Outlook 2003; ANSI refers to the older type that's limited to 2GB. Setting the Preferred PST Mode adds a string registry value named NewPSTFormat to the HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook subkey. NewPSTFormat can have the following values:

Prefer Unicode PST: 0 (default)
Prefer ANSI PST: 1
Enforce Unicode PST: 2
Enforce ANSI PST: 3

By using a value of 2 or 3, you can restrict all new .pst files to either the old format or the new format.

The corresponding set of policies listed in Group Policy Editor (GPE) under User Configuration\Administrative Templates\Microsoft Office Outlook 2003\Miscellaneous\PST Settings goes one step further than the ORK tools and provides a way to limit the growth of both old and new .pst files without totally restricting their use. A bit inconsistently, the policies use the term "Large PST" for the Unicode format and "Legacy PST" for the older ANSI format, but for each .pst format, you can set an absolute maximum size and a separate "Size to disable adding new content." The default maximum size for a Unicode .pst file is about 20GB.

With this array of policies and registry settings, Outlook--particularly Outlook 2003--lets you control end users' access to .pst files, set .pst file size limits, control the type of .pst files Outlook 2003 users can create, prohibit the use of new .pst files, and even suppress the menu command for opening an existing .pst file.

Reader Comments

Great information. I am starting a project now to figure out what to do the PST problem at Bank of America. 2003 seems to have the features I am looking for. I will hold on to your article for future reference. Thanks.

When using the CustomInstallationWizard to create your transform for Outlook2003 deployment, you can also choose Prefer ANSI so that the OST will also be legacy compliant. This string is found under ChangeOfficeUserSettings>MicrosoftOfficeOutlook2003>ExchangeSettings>ExchangeUnicodeMode>...

Great article thanks for the work.

Sir/Madam, Which all are the file formats that the PST Supports..? The requirement is that I am creating an application that mimic Outlook.I need to save the contents into a file similar to pst. Caqn i know which all are the file formats the PSt supports.? How can i save the data into my PST.?

So much is said about outlook 2003, but can some one elaborate whether/ how does outlook 2003 allow multiple pst files..eg, if u have configured 2 accounts in outlook 2003, and want it in such a way that each different account is configured in each pst file..(please don't suggest use of profiles) Secondly, when u confiure email accounts, it allows u to specify the location as to where you want to physically store the pst file, but it doesn't with configuring hotmail accounts, and it stores somewhere by default.. Hope this articel can focus on the areas i have raised.. Thanks, adn if this article is updated in regards to my focus areas, please do let em know via email..

Very good article, but i would just like to mention that you can not set values for "Default location for .pst files" using Group Policy Editor. You have the same problem with OL2000 see KB 222237 Regards

Article is very good, but i want to know how to copy a .pst file when outlook is open(i.e if i try to copy it says some files are locked cann't copy).Any solution for this please mail to me. Thank you.

Hi, good article! How do you move a Office 2003 PST to Office XP? Seems it is backwards incompatible. Please help!

Fascinating. The network operators' POV seems to be to limit PST use and functionality; whereas users want more functionality

Great article!!To access an Outlook 2003 .pst file from a different computer that has an earlier version of Outlook installed, see http://support.microsoft.com/?kbid=830336

Nice article - but using the DisablePst reg setting disables the WSS features, you cannot link to the wss contact lists and calendars. Question: Do you know if there is a way to limit the PST sie without limiting the OST size as well? We tried to use the GPO you mentioned but it affects both.

I am trying to export my emails from Outlook 2003 to Outlook 2002. When I try and Import them using the 2002 version, an error message appears saying that the .pst file "is not compatable with this version of the Personal Folders information service". Can you tell me how to get around this? Many thanks.

Great Article: I am having this problem as well- "I am trying to export my emails from Outlook 2003 to Outlook 2002. When I try and Import them using the 2002 version, an error message appears saying that the .pst file "is not compatable with this version of the Personal Folders information service". Can you tell me how to get around this? Many thanks."

Looking for a way to reduce the size of the existing .PST files for our users. Many emails are retained due to long term ongoing projects - 2 - 3 - 4 -5 years. Looking to convert to a file we can save on a CD - maybe as a text RTF type file that can be searched and read from the CD? Any suggestions?

Good information, but I have a problem with my PST password, I forget it after 3 years, how could I crack this file, please help!

many thanks to Luigi for the item as to how to save a PST file in a format which Outlook XP can read. Really nice.

If you are looking for a way to reduce the size of your PST files, esp. archive ones, you might want to look at PSTCompactor (www.PSTCompactor.com). Compresses attachments, forces compaction, etc. Worked well for us - got just under 38% back.

Thank you for the informtion. How do I move existing XP.PST Files to the new format within Outlook 2003? One of my Outlook 2003 Files has more thang 1.5 Giga, so it is mandatory to convert. But I want to be sure how to proceed to not lose datas and the Outlook 2003 Organisation (i.e. rules and views).

Fo' shizzle. This owns.

That's great help ! thanks to Sue Mosher. Now I can use Outlook to store my unicode information.

The article was helpful, but I'm trying to block users access to create or read pst files in Outlook 2002. We aren't ready to move to Office 2003 yet. I've tested the DisablePst registry change, and tried group Policies, but haven't had total success yet. We are using Exchange 2000, and want to remove all access to user pst files. Any other ideas? Thanks

The reg fix worked for us! By setting the unicode value, our CFO's OST was able to grow past the acsi 2gb limit

Looking for a solution for archiving your PST-File onto CD? Check out WN Mailkeeper from http://www.wickett.net/renderPage.asp?Page=WNMailKeeper

Great information. But how does a non-technical person such as myself (using Windows XP and Outlook 2002) read a .pst file from a cd? I know you said to put it on the hard drive...but i really have no clue WHERE on the hard drive and how do i try to read the file once i put it on the hard drive. Please Help! I'm trying to view an old .pst file from an old office computer to determine if it's still relevant to store.

Microsoft says the NewPSTFormat key should be a DWORD, not a string. The NewPSTFormat key doesn't seem to work with Outlook 2003 and IMAP PSTs. If the key doesn't exist, old-style PSTs are always created when you add an IMAP account to a profile. If the key is set to 2, to enforce the use of new-style PSTs, that seems to cause problems when trying to create IMAP accounts.

For all you people who are asking why the formats are not backwards compatible.. its probably because you are exporting a unicode file. Instead do an ascii export. Just my thought...

Do you know where I can find pst file converter and pst password?. Any help is much appreciated!

I'm looking for a way to retain the original location of a user's PST file when migrating from Office XP to Office 2003. I've been playing around with the Custom Install Wizard from the Office 2003 Resource Kit and have created a Outlook PRF file that I would like to use for both upgrading users to Office 2003 and also for fresh installs of Office 2003. The user's Outlook profiles seem to loose the paths to their existing PST files during the upgrade process. The Outlook profile takes on the default PST location as set within the PRF file instead of leaving the existing PST paths in the Outlook profile intact. I'm concerned that if I leave this setting out of the PRF, I won't be able to specify the default location of a PST if one doesn't already exist? Doesn't "default" mean "use this value if one isn't already specified"? It seems more like "override" at this point. Well my existing users already have values specified for their PSTs in their Outlook profile. It just seems that the "default PST location" (as set by the PRF file) is overriding the existing values in the user's Outlook profile during the upgrade process. I'm planning on rolling out the software upgrade via group policy, and would want to use a single policy for both upgrading to Office 2003 as well as fresh installs of Office 2003. I'm planning on using the same MST (transform) and PRF (Outlook Preferencee file) for both upgrading and doing fresh installs of Office 2003. I just need a way to migrate the user's paths to their PSTs as set in their Outlook Profile without loosing them, while still being able to set a default value to where new PSTs should be created if a user doesn't already have a PST in their profile. Any ideas?

I just discovered the that within the outlook.prf file is a value named "OverwriteProfile", which was set as follows: OverwriteProfile=Yes I have changed this to: OverwriteProfile=Append which is only supposed to attempt to add the services that you specified in the PRF file to the existing profile instead of overwrite the existing profile. I was creating my original PRF within the Custom Install Wizard, which automatically assigned OverwriteProfile=Yes. I didn't see this until I opended the PRF within notepad and made the change manually. Now that I've got it working for the default profile. I'm trying to find a way to enumerate all the profiles. I want to change each existing profile, not just the default one. I'm not sure if there's a way to do this within the PFR that is called my my transform during the Office 2003 migration from Office XP. Maybe this will have to be done after the migration with a script that can enumerate each profile and run the PRF on each outlook profile individually. I've heard of a tool called newprof and migprof that might be able to do this. Does anyone know how to enumerate a listing of the profiles for use in a script so that each and every profile can be migrated (instead of just the default one)? I would like to find more information about the PRF setting: ModifyDefaultProfileIfPresent=True (or False). Microsoft released a technical paper called: PRFwhitepaper.doc that says: "the setting ModifyDefaultProfileIfPresent can be set to True or False. When set to True, Outlook will modify the default profile even if the new and existing profile names are different." I can set this setting to "true" to migrate the default profile, but do I need to change it to false in order to modify the other profiles? Once again, how do I enumerate the other profiles to migrate them all?

Has anyone had any issues where the archive folder that is used in Outlook 2002 is not able to be archived to once over in Outlook 2003? You can open it and move data out of it but it cant be used as the default archive folder.

As mentioned in an earlier comment, we would like to back up our .PST file, while Outlook is in use, but apparently, MS has locked it in a way that our previous backup software (Iomega Quicksync) can do it anymore. (It was able to back it up in 2000). Is there away to edit Outlook 2003 to unlock the .PST file, or is there another Third Party software out there that can back up this locked .PST file.

I am trying to make a PST file so that it can be opened and read but not written to nor deleted from!!! Is there a way to do this??? Can anyone help me??? Cheers

I want to do full text search on the body of e-mail in Exchange. How do I get it out of Exchange in a manner that I can subsequently load into an RDBMS, say, via CSV? Is this asking for too much? Thanks in advance for any ideas.

All our users store their PST files on a network drive in a 2003 AD Domain based environment (they have pop mail accounts with an external provider). I want to ensure that when they cannot connect to the network for whatever reason they do not have the option to create another PST file (in their local profile). Can I use the disable registry setting above. If so would I have to delete any PST files that already exist in the local profile ? They are all on Outlook 2000-3. Your advice would be very much appreciated.

Ron Marek, there's no magic setting in Outlook 2003 to make a PST file readable by another program while Outlook has it open. You might see if any of the other backup utilities listed at http://www.slipstick.com/config/backup.htm#tools can help.

garry_wordsworth, no, PST files are not designed for read-only access.

Darran Beard, if it's not an Outlook 2003 PST and you're connecting to Exchange 2000/2003, the issue might be that the PST isn't Unicode compatible, but the data is. Why not just switch to an archive file in the new format?

Ciji Joseph, a .pst file doesn't "support file formats." It stores Outlook data.

Mark, you are correct that Outlook 2003 PST files are not backwards compatible. While using Outlook 2003, create a new .pst file in the Outlook 97-2002 format, then export all your data to it. You'll be able to open that file in Outlook 2002 or earlier versions.

Rosh, IMAP4 accounts always use a separate .pst file for each account. For POP3 accounts, you can use a Rules Wizard rule to refile messages to different folders.

Roger Bolle, you can export rules through the Rules Wizard dialog. It's not obvious how, but you can use a PST file to back up your views. Here's a link to an article I wrote on how to manage this: http://www.exchangeadmin.com/Articles/Index.cfm?ArticleID=8650

Gina Tobar, Outlook doesn't care where on the hard drive you put a .pst file. You decide where you want to put it. After you copy it from the CD, right-click the copy on your hard drive, choose Properties, clear the Read-only check box, then click OK. After that, you can open the file in Outlook with the File | Open | Outlook Data File command. Use the Folder List to see what folders are in the file and to navigate to them.

Rick Rooney, good point about WSS features! It makes sense, given that WSS folders are cached in a .pst file. Re: PST vs OST file size, they're essentially the same file, except for security so I'm not surprised the GP setting affects both.

I have a client on Windows XP Home, who for some time only had one account between the whole family. They used the same Email program for their mail. A Mail filter moved email to a special folder for each account. I've now set them up with separate accounts in Windows XP. The problem now is moving all the email for one person from the existing Outlook 2003 file/folders, to the new account. The contacts are easy of course.

I need to incorporate in an outllok 2002 vertion many .pst created with a 2003 one...can you give me advise? Thank you.

is there a way to add more than two accounts,will i hneed two .pst files ?

Daniel, as stated in an earlier comment: While using Outlook 2003, create a new .pst file in the Outlook 97-2002 format, then export all your data to it. You'll be able to open that file in Outlook 2002 or earlier versions.

Anonymous, you can add many accounts. The details depend on the type of account and the Outlook version.

http://support.microsoft.com/default.aspx?scid=kb;en-us;839109

move outlook 2003 back to office xp...problem solve http://support.microsoft.com/default.aspx?scid=kb;en-us;839109

Where in the registry does Outlook 2000-2002-2003 point to the different .pst files( archived, current mail, personal folders) stored locally on your system. Don

Impressive article, but way too much for me. All I want to do is to specify the location of the outlook 2003 data files. For safety reasons, I keep all data files on a physically separate hd. However, it seems to be almost impossible to change the default location of the pst and dat files without messing up something or other. Does anybody know how I can move this stuff off the C: drive?

I still find one question unanswered. Can any one reply to vedhapuri@qatar.net.qa asap pls ? In OL 2003 how to set different data files for multiple email accounts ? Thanks Balaji

HI, Is there any way to Add two Pst files in outlook 2003 using prf files??? Any help Will be much Appreciated> Thanks Arun

I have a problem where I can back up my .pst file fine but I will only be able to see part of the e-mails in my inbox. Can anyone help ? Cameron.

At work we are running outlook 2003 I have pst file with a lot of info in it so I borrowed a friends usb sd card reader copyed the file and then plugged the sd card into my pda and copied it there when i try to import the file i get an error the file .pst is not compatible with with this version of the personal folders information service I know about the knowledge base article and that only applys when importing to an older outlook these are identical and i mean that litteraly any help would be much abliged

I have a new colleague joining my department. We each have a GID laption and will have a common Server space for our data, but is there any way we can both access the same pst files at the same time in outlook? I am trying to figure out how to give him access to historic emails as well as keeping access myself.

Do the .pst files include attachments? If not if isthere some way to define where they are kept etc. Thank YOu

How can you tell what version a previously created .pst file is? Also, I have tried the "2" and I still get the option to create the old style .pst. Does it just ignore it and create it as Unicode anyway? Thanks, DCS

OK, one other thing... I'm sure I know the answer already, but... Is it possible to share a .pst file between users? Or a folder within a .pst?

OK, here's a fun one....I recently reinstalled Windows XP Pro SP2 on another harddrive in my computer and just copied the .pst file over after I got Office 2003 installed. Now I have 2 copies of everything in Outlook. Now my Contacts are duplicated and when I start typing in the "To:" field when I send an email, it pulls from the wrong Contacts.....how can I get rid of the other Personal Folders folder in Outlook? Help?

Anonymous -- You apparently have a "ghost" PST file. The one sure way to get rid of it is to start over with a completely new mail profile and make that .pst file the default store for it.

Don, mail profile information for Outlook 2002 and 2003 is in the HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles registry key. Each profile has its own key.

> Is it possible to share a .pst file between users? Or a folder within a .pst? Outlook can't share its files directly. See http://office.microsoft.com/en-us/assistance/HA011477571033.aspx for an article by Outlook MVP Eric Legault on various ways to share Outlook data. YOu'll also find a list of third-party sharing tools and other information at http://www.slipstick.com/outlook/share.htm

> Do the .pst files include attachments? Yes, all attachments to Outlook items are stored in the .pst file.

> In OL 2003 how to set different data files for multiple email accounts ? IMAP and Exchange accounts get their own stores automatically. For POP accounts, you can use Rules Wizard rules to move incoming messages into different PST files.

> Is there any way to Add two Pst files in outlook 2003 using prf files??? Yes. The easiest way is to use the Custom Maintenance Wizard from the ORK to generate the .prf file.

> How can you tell what version a previously created .pst file is? Also, I have tried the "2" and I still get the option to create the old style .pst. Does it just ignore it and create it as Unicode anyway? If you open the file in Outlook, you can go into its properties there. If it doesn't say it's an Outlook 97-2000 file, it's Unicode.

>> All I want to do is to specify the location of the outlook 2003 data files. For safety reasons, I keep all data files on a physically separate hd. However, it seems to be almost impossible to change the default location of the pst and dat files without messing up something or other. Does anybody know how I can move this stuff off the C: drive? << Shut down Outlook. MOve the file. Restart Outlook. It should ask you where you put the file.

>> I need to incorporate in an outllok 2002 vertion many .pst created with a 2003 one...can you give me advise? << Get a copy of Outlook 2003 so you can open it. You can then create a new .pst file in Outlook 97-2000 format and export to it from the Outlook 2003 .pst file.

If my Personal Folder has reached its maximum size, how can I manually split it, so users can add more email to a specific pst folder?