Microsoft plans to open up Outlook PST data format

Microsoft said today that it plans to open up the PST data format commonly used within Outlook.

In a MSDN blog posting, Paul Lorimer, Group Manager of Microsoft Office Interoperability, confirmed Microsoft want to improve platform-independent access to email, calendar, contacts, and other data generated by Microsoft Outlook. The PST format is used to store data ranging from email to calendar and contacts and allows for users to export and import that data within Microsoft Outlook.

According to Lorimer: "In order to facilitate interoperability and enable customers and vendors to access the data in .pst files on a variety of platforms, we will be releasing documentation for the .pst file format. This will allow developers to read, create, and interoperate with the data in .pst files in server and client scenarios using the programming language and platform of their choice. The technical documentation will detail how the data is stored, along with guidance for accessing that data from other software applications. It also will highlight the structure of the .pst file, provide details like how to navigate the folder hierarchy, and explain how to access the individual data objects and properties."

Microsoft says the documentation is still being worked on and is in its "early stages". With an Office 2010 public beta due next month it's reasonable to assume we will hear a lot more about Office 2010 in general at next months Professional Developers Conference in Los Angeles. Allowing the PST format to be documented and open will allow web mail providers like Gmail and social networking sites like Facebook to better import data from Microsoft's Outlook application.

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41 Comments

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I'm not 100% sure I see the point, since Outlook's already got a pretty decent object model--you already can read just about anything using even VBScript.

Maybe if you don't already have Outlook installed, I suppose, but then parsing a PST directly is going to be way more error-prone than just using the existing API.

I expect to see a lot of tools that will be corrupting PSTs in the future, at least initially...

It would be much-much better, if they fix their Outlook to allow it to have more than one Exchange account in the same profile. It is really difficult to use different Exchange servers (for an example, when you are the consulter with multiple customers), OWA isn't the solution

Why would you want to mix multiple exchange accounts in one profile? That just sounds messy. Outlook dumps everything up to the Exchange server. Even small settings such as what view you set on a specific folder. So mixing Exchange accounts inside individual profiles would be a mess.

You'd have to pick which account gets what setting synced to it for everything.

Why not do the simple and much much better solution of making seperate profiles for them?

Frazell Thomas said,
Why would you want to mix multiple exchange accounts in one profile?


Because I'm monitoring few customers accounts (usually we get an exchange account on the customer's server) plus I have a company's exchange server. OWA isn't really the option, IMAP too (almost always an exchange server is accessible over OWA only - http passthrough)

This is fantastic, and it's about time. It won't change much for Outlook plug/add on developers, though. Changing the application model so it's more open would be just as important as this.

Its time for the Thunderbird and Evolution team to come up with a decent open source alternative to Outlook. I could not completely turn open source because I have almost 10 years of emails in pst.

They need to redesign PST's from the ground up. The ost/pst system just does not keep up with current mailbox use.

I have this strange feeling by doing this and licensing out the Exchange ActiveSync Microsoft is setting themselves up for a major competitor to take some marketshare away from them.

i use thunderbird and it local directories for my small business.
gmail for my domain for the usual cloud access and archiving my email in a shared local directories.

thunderbird stores in separate files for each folder in the archive, therefore its happy unless to people enter the same folder.
ok for small business


unlike outlook where its all in one pst.

Um, that's a definite NO. As popular as Exchange is, they wouldn't want to give away the Windows licenses required for Exchange to run. Not to mention that you need .NET to run Exchange, and even though there's a cross-platform implementation of .NET, I doubt it's stable enough to run a mail server the way it needs to be run.

IMO, Exchange is the selling point of Windows Server. I have a very limited knowledge in the server world, but it seems that all the other features are easily achievable with non-server versions of Windows, Linux and Mac.

Shadrack said,
IMO, Exchange is the selling point of Windows Server. I have a very limited knowledge in the server world, but it seems that all the other features are easily achievable with non-server versions of Windows, Linux and Mac.



I thought it would be SharePoint

Except for the licensing terms which say do not use as a server. IIS is included in Windows Pro for developer use only, not for production use. Read the fine print.

This is great news for third party e-mail application developers -- finally, you will be able to import your information from Microsoft Outlook without having to use several other tools.

Yes I completely agree. I've never been able to figure out how to programmatically access PST files and have had to rely on other developer components or programs to export to a universal medium such as CSV. This is great since I can finally access those PST files myself and save tons of time and effort.

BTW - how in the hell did those other developers ever get access to PST files? I never figured that part out either. My guess is that they were former Microsoft employees that had some sort of inside knowledge on the inner workings of PST files and JET storage (which I think the PST files use).

Nighthawk64 said,
This is great news for third party e-mail application developers -- finally, you will be able to import your information from Microsoft Outlook without having to use several other tools.

+1

Tim Dawg said,
Yes I completely agree. I've never been able to figure out how to programmatically access PST files and have had to rely on other developer components or programs to export to a universal medium such as CSV. This is great since I can finally access those PST files myself and save tons of time and effort.

BTW - how in the hell did those other developers ever get access to PST files? I never figured that part out either. My guess is that they were former Microsoft employees that had some sort of inside knowledge on the inner workings of PST files and JET storage (which I think the PST files use).


reverse engineering, patience and lots and lots of coffee

Having the .pst file opened up will be a godsend to anyone who wants to move outlook data to another program. A .pst import method in a lot of other email/pim applications will be nice to see.

Because the vast majority of IT groups put space limits on exchange mailboxes -- I fill up my tiny little 250mb box in about a week.

carpediem said,
Why would you even wanna touch pst-files if you have an exchange server?

Because exchange servers come crippled unless you pay a lot of $$$ in licensing to Microsoft to make the email inboxes larger. As it is now, I HAVE to move all my exchange server emails to a .pst "archive" folder yearly or else my exchange email inbox will fill up. Doesn't help that I get 5-10MB attachments in my emails daily.

The licensing limitation was explained to me be our IT department. I thought it was silly, especially coming from a Linux server background. One thing I've learned, however, is to not be a problem for IT. So I don't fight it. The archive files work fine and are completely searchable. I have them on my laptop and on our fileserver for backup.

Tom W said,
And how many consumers at home with their new shiny Windows 7 laptops have an exchange server exactly?


I answered the one above but something went wrong... He said he wanted to hook up owa with pst and that would of course require an exchange server.

Further on... There's no license that covers the size of the users mailbox. The IT department that told its users so are lying. Exchange 2003 had a limit on 16gb for the database but that can be changed with a registry value. Exchange 2007 have much much higher limits on the database size.

Shadrack said,
Because exchange servers come crippled unless you pay a lot of $$$ in licensing to Microsoft to make the email inboxes larger. As it is now, I HAVE to move all my exchange server emails to a .pst "archive" folder yearly or else my exchange email inbox will fill up. Doesn't help that I get 5-10MB attachments in my emails daily.

The licensing limitation was explained to me be our IT department. I thought it was silly, especially coming from a Linux server background. One thing I've learned, however, is to not be a problem for IT. So I don't fight it. The archive files work fine and are completely searchable. I have them on my laptop and on our fileserver for backup.


Unless you have exchange 5.5 or older, your IT department must be lying. The size of each users mailbox can be set by the exchange admins and no licence model restrics the size that a users maibox can be.

For as many emails as I get I have to use multiple PST files at work. I think we have ~100mb limit, which is just silly, especially when receiving hundreds of emails per day, many of which have 1mb plus attachments.

Shadrack said,
Because exchange servers come crippled unless you pay a lot of $$$ in licensing to Microsoft to make the email inboxes larger. As it is now, I HAVE to move all my exchange server emails to a .pst "archive" folder yearly or else my exchange email inbox will fill up. Doesn't help that I get 5-10MB attachments in my emails daily.

The licensing limitation was explained to me be our IT department. I thought it was silly, especially coming from a Linux server background. One thing I've learned, however, is to not be a problem for IT. So I don't fight it. The archive files work fine and are completely searchable. I have them on my laptop and on our fileserver for backup.


I don't think theres any license model that restricts the size of each inbox...your it department sets it depending on hardware

Shadrack said,
Because exchange servers come crippled unless you pay a lot of $$$ in licensing to Microsoft to make the email inboxes larger. As it is now, I HAVE to move all my exchange server emails to a .pst "archive" folder yearly or else my exchange email inbox will fill up. Doesn't help that I get 5-10MB attachments in my emails daily.

The licensing limitation was explained to me be our IT department. I thought it was silly, especially coming from a Linux server background. One thing I've learned, however, is to not be a problem for IT. So I don't fight it. The archive files work fine and are completely searchable. I have them on my laptop and on our fileserver for backup.

I agree with the other posts. I'm an Exchange consultant and I can tell you that there are no licensing restrictions on mailbox sizes. There USED to be an information store size limit of 16GB but Microsoft lifted that with a service pack and registry entry. Now the information store limit is 75GB I believe. Past that you would have to step up in version to create additional storage groups or increase the information store size. I don't normally see these limits imposed at all but the largest cheapest companies considering how cheap storage is now-a-days.

Yeah, I seem to remember the 16GB limit and I think we are still on that. Everyone here thinks that is obscenely small considering there are 20 of us that have to limit our emails to this 16GB limit. Thats less than a GB a piece. On top of that we have policies that say we have to CC all these administrators on every email. Doesn't help that the exact same 5-10MB email attachment hit 6 of our exchange server's inboxes needlessly.

I probably won't push the issue though. I've learned to choose my battles. This is one of those things where my email works, I have a simple way with dealing with the limitation forced on me by IT, and therefore don't have any real issues.

Shadrack said,
Yeah, I seem to remember the 16GB limit and I think we are still on that. Everyone here thinks that is obscenely small considering there are 20 of us that have to limit our emails to this 16GB limit. Thats less than a GB a piece. On top of that we have policies that say we have to CC all these administrators on every email. Doesn't help that the exact same 5-10MB email attachment hit 6 of our exchange server's inboxes needlessly.

I probably won't push the issue though. I've learned to choose my battles. This is one of those things where my email works, I have a simple way with dealing with the limitation forced on me by IT, and therefore don't have any real issues.


It's easily expandable with just a registry value if you have Exchange 2003 with SP2, so there's no excuse for those lazy administrators

Tim Dawg said,

I agree with the other posts. I'm an Exchange consultant and I can tell you that there are no licensing restrictions on mailbox sizes. There USED to be an information store size limit of 16GB but Microsoft lifted that with a service pack and registry entry. Now the information store limit is 75GB I believe. Past that you would have to step up in version to create additional storage groups or increase the information store size. I don't normally see these limits imposed at all but the largest cheapest companies considering how cheap storage is now-a-days.


I was thinking that exact same thing but did a search before I responded and was stunned when I found out Exchange 2007 Standard's mailbox limit is 50GB http://technet.microsoft.com/en-us/library/aa997432.aspx

Thanks Shadrack for the info

winrez said,


I was thinking that exact same thing but did a search before I responded and was stunned when I found out Exchange 2007 Standard's mailbox limit is 50GB http://technet.microsoft.com/en-us/library/aa997432.aspx

Thanks Shadrack for the info


from the technet article:

The Exchange Server 2007 Standard Edition hard coded licensing database size limit of 50 GB can also be increased by creating the Database Size Limit in Gb registry value.

carpediem said,
It's easily expandable with just a registry value if you have Exchange 2003 with SP2, so there's no excuse for those lazy administrators ;)

Yes they are probably just lazy. Oh well *sigh*.

carpediem said,
Why would you even wanna touch pst-files if you have an exchange server?


You do know that outlook caches the Exchange mailbox on the local computer in .pst format right?

Ken Mickeletto said,
How about making it so you can store PST's in a share and be able to access it from OWA. That would be impressive!



I had that setup for a couple users by accident on a SBS 2003 box and it worked