Convert .OST to .PST


  • Im trying to create an app that converts an .ost file to .pst. An .ost file is a Microsoft Exchange email file and in order to read an .ost file offline you need it to be converted to .pst.

    I know theres tools available for office 2000 for free but this does not work with Office 2003 only ones available need to be paid for......if you need more info on this please see http://www.nucleustechnologies.com/exchange-ost-recovery.html

    So this leaves me to ask i know how to convert files but what encryption do i need to lets say decrypt the ost file then pack it back in a pst form so its readable in Office 2003 as a .pst file?


    Friday, January 05, 2007 2:12 PM


  • The .ost and .pst file formats being proprietary to Microsoft, there is no documented way to do this, much less with VSTO (which is the topic of this forum).
    Friday, January 05, 2007 4:03 PM

All replies

  • The .ost and .pst file formats being proprietary to Microsoft, there is no documented way to do this, much less with VSTO (which is the topic of this forum).
    Friday, January 05, 2007 4:03 PM
  • Thanks for your reply. If this is proprietary to MS how do other manufacturers work this out? Or is this an advanced topic or something?


    Friday, January 05, 2007 5:58 PM
  • Reverse engineering and hacks.
    Friday, January 05, 2007 5:59 PM
  • I would have thought MS would have jumped on them like a ton of bricks!!! however if i wanted to do this for personal reasons are there any articles i could read you know of?
    Friday, January 05, 2007 6:12 PM
  • Can you tell me which tools are available? I'm still working with Outlook 2000. As my PC was infected I had to format it and now I can't read my ost file anymore. I'm desperately seeking for a free tool to convert it to pst. As just a private user it's too expensive for me to buy the software.

    Waiting your news, regards Dini

    Saturday, June 02, 2007 10:52 PM
  • Dini000, read the earlier posts in this topic. AFAIK, there are no free tools for this task.
    Sunday, June 03, 2007 1:09 PM
  • Thanks for your reply. I had read the earlier posts and I did try the demo version of the repair software. And it works super, but 70 dollar is just too expensive. They offer a file repair service to, which will cost minimum 50 dollar. I look further for a (cheaper)solution. Regards Dini
    Sunday, June 03, 2007 10:29 PM
  • I think its rediculous that one has to pay to have data within an OST file converted to PST. Its really not rocket science - someone's just trying to make a quick buck! After all - both OST and PST are read by Outlook and you own the data....! Not as if it's some dodgy 3rd party software that you're trying to export from...into PST!


    Companies spend thoundsand on Exchange 2003 and Office 2003 (including CALS) and a simple export from OST to PST is not available...? Just speaking my mind...as an Exchange engineer, I think certain tools should be available to simplify support. The again, its not as if I would use this utility on a daily basis....

    Monday, June 04, 2007 4:58 PM
  • valdarama, you should never need such a utility in an Exchange environment, since a user can always export to a PST file (unless that's blocked with GPO) and ost files are not a backup solution. Where it comes up most often is in situations where the user left a company with only an .ost file and now can't get to that data (which, some might argue, the company owns, not the user).


    In any case, the subject is very, very off-topic for this forum, which deals with issues related to programming VSTO.

    Monday, June 04, 2007 5:31 PM
  • Sue and everyone,


    My apologies for using this thread to vent my frustration. Was not my intention to hijack the thread.


    Sue - have you actually worked in an exchange environment? I am a systems administrator/exchange engineer supporting an organization with one of the largest Exchange 2003 environments in the world, including multiple Cluster environments and literally hundreds of Exchange servers accross the globe. When it comes to process management, these guys are pro.


    Yes, there are guidelines which organizations follow, but no process is fool-proof. You are correct with regards to potentially needing such a utility in the case where a user leaves the company. Note that the users data is owned by the company. Under most circumstances, the data can be retrived from tape, however, this may have cost implications, depending on your DR solution..


    Lets say the OST file was available for a user who has resigned and his/her user profile has been discarded. The systems administrators or Exchange admins would find such a utility usefull, as it would enable us to provide better service delivery to our clients, instead of opting for the complex solutions, such as having to request a restore or purchasing pricey converter software which will only be used on rare occasions. There would be no security threats either, as Exchange administrators have the necessary rights to open anyones mailbox anyway.


    I must admint that it is quite rare to have the need for converting OST to PST....so I guess it is understandible that a free Microsot Converter does not exist. It's a "nice to have".


    Once again, my apologies....I googled OST converter...etc, came to this site and thought I'd provide some input.

    Tuesday, June 05, 2007 7:44 PM
  • Hi Sue

    I could not find a way to export outlook.ost to a PST file. I would appreciate if you could point me to the right menu options.

    Wednesday, June 06, 2007 6:17 PM
  • prapu, it sounds like you've missed the point of this discussion, two points actually. The first is that this is not the forum for asking usage questions about Outlook. The second is that there is no export explicitly from an .ost file to a .pst file. Instead, you use the File | Import and Export command to export to a .pst file from the Exchange mailbox, which will be cached in a local .ost file for most Outlook 2003/2007 users with Exchange accounts.
    Wednesday, June 06, 2007 7:30 PM
  • Two points:
     - First, is there a utility that can convert an .ost from Outlook 2007 to a .pst (everyone seems to be up to 2003 only)?
     - Second, why doesn't Microsoft (ahem) supply a utility with Exchange to convert .ost to .pst.  This is pretty much a no-brainer in my opinion.
    Thursday, August 30, 2007 2:46 AM
  • Sue,


    One more question on .OST files :-


    One of our customers is worried that if a user loses his laptop some one could decrypt the .OST and .OAB files to gain personnal information.


    What is the encryption used for .OST and .OAB files please , so I can put the customers mind at rest.


    Thanks  Andy S.


    Monday, January 21, 2008 2:37 PM
  • A quick Google or MSN search would turn up several applications for cracking OST file security. The microsoft.public.exchange.clients newsgroup probably would be a better place to discuss your concerns.
    Monday, January 21, 2008 4:38 PM
  • I've bought 2003 BUT still this action is only possible if you have access to an Exchange Server. I've searched again on the net and I found a service to whom you can send your file for conversion. I did it and it's great. They give a perfect and quick service for a reasonable price. See http://www.pcsadmin.com

    Sunday, March 30, 2008 12:37 PM
  • There is a good online service to recover data from OST files.
    Also they solve any other problems with OST or PST files.
    I’ve used it. All OK.
    Friday, January 22, 2010 9:36 AM
  • To Convert OST into PST I would like to suggest you to use Unistal's Quick Recovery for MS Exchange software which can easily convert inaccessible, deleted, damaged or corrupt Microsoft Exchange Offline Storage file (.OST) to Personal Storage file (.PST).

    You can download the demo version of this software from http://www.unistal.com/download-ost-pst-conversion-software.html and if you find that this utility is as per you expection then go for full version.

    Friday, May 21, 2010 10:30 AM
  • hie frnd,

    same som sought of issue i was also facing in gone past, i import that file in Outlook Express and then i again import it into Outlook.



    Wednesday, June 02, 2010 12:34 PM
  • Its true but, it wont allow you to save the conversion unless you buy the program.
    Tuesday, August 24, 2010 2:02 PM