I have Microsoft Outlook 2007 installed and use IMAP for all my mail accounts. When I updated to Windows 7 I had to reinstall Outlook and thus download all the headers again. I ended up downloading everything again, but I would want to prevent this in the future.

Is there a way to import my Microsoft Office Outlook Personal Folders (.pst) or Offline Folder (.ost) files into the new installation, so I don't have to download all the headers again?

Edit: I checked the extension of the files in my current Outlook folder, which are .pst files, is it possible Outlook changed them to .ost files when I was messing around with my Outlook settings? I've changed my question to import .pst or .ost.

Edit2: I tried exactly that and even made sure they had the correct name, but then Outlook would crash on me. I guess there is more to it than just the file names... I also tried some programs to restore .ost files, which actually managed to get files out if it, but also tried to empty my wallet... I'm hoping for a kick-ass hacky way to get it working anyway!

  • Apperently .ost files are linked with an Exchange account or else can't be opened...
    – Ivo Flipse
    Jul 22, 2009 at 7:11

6 Answers 6


I have had success with two different methods:

Method A

  1. Save your pst/ost files (copy to a safe place via windows explorer)
  2. Re-install Outlook and set up the account, but prevent it from downloading anything.
  3. Note the location of the pst/ost files for the new Outlook installation
  4. Close Outlook
  5. Via explorer, replace the new installation's pst/ost files with your saved ones
  6. Restart Outlook

Method B: Also I have used the previously mentioned Outlook import feature:

  • File > Import and Export > Import from another program or file > Personal Folder File (.pst) > locate PST/OST > Import

As for the difference between PST and OST files:

  • OST files cache the files from the exchange server; they are "copies"
  • PST files exist only on one computer; they are not stored on the Exchange server

Sure... there are 2 ways:

  • just put your .pst file at the default location BEFORE you start outlook for the first time (usually that's somewhere under your user folder/appdata/microsoft/outlook/...)

  • or you can open outlook first, and then open your .pst file and then mark it as the default pst file and then remove the original one.

Concerning the .ost files: have you tried the same? I think you will have to configure outlook first (the IMAP account settings) but don't download the headers, then shut down outlook en copy your old .ost and .pst files over, and then restart outlook... not sure if that will work though...

Maybe this can be interesting as well: Repair a .pst or .ost file in Outlook

  • Excuses for updating my question, your solution probably works for .pst files, but I guess my files "magically" transformed to .ost files
    – Ivo Flipse
    Jul 16, 2009 at 12:23

You can add PST files right into an existing Outlook configuration.

For Outlook 2007:

Tools / Options / Mail Setup tab / Data Files... Then press the "Add" button, choose between the new format PST or the old 97-2002 format. Then browse to where your file is located.

It should show then in the folder view of Outlook.

I also create local PST files for archiving "stuff". I then move the PST files when I get a new system, it's very handy. There are some Outlook systems that have policies that prevent creating PST files. Hopefully you won't get involved in that.


File > Import and Export > Import from another program or file > Personal Folder File (.pst) > locate PST/OST > Import


I would recommend the Import method's described in the other answers. Moving the pst file without importing it can often cause very weird errors because some absolute paths seems to be stored in it.


This project seems to work perfectly: https://github.com/mkorthof/ost2pst . No restrictions like all the other commercial tools that a Google search turns up.


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