By default, .pst files are in the Unicode format in Outlook 2007 and in Outlook 2003. Additionally, the overall size of the .pst files has a limit that is more than the 2-GB limit that is imposed by the ANSI .pst files. By default, the limit for a Unicode .pst file in Outlook 2007 and in Outlook 2003 is configured to be 20 GB. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
As in earlier versions of Outlook, Outlook 2003 Internet Message Access Protocol Version 4rev1 (IMAP4) accounts and HTTP accounts use .pst files that do not use the Unicode format. Therefore, the .pst files for IMAP or HTTP accounts in Outlook 2003 are limited to 2 GB. In Outlook 2007, the Internet Message Access Protocol Version 4rev1 (IMAP4) accounts and HTTP accounts do use Unicode format .pst files and are not limited to 2 GB.
If you want to access an Outlook 2007 or Outlook 2003 .pst file from a different…
- Start Outlook 2007 or Outlook 2003.
- On the File menu, click Data File Management, and then click Add.
- Click Outlook 97-2002 Personal Folders File (PST).
- Click OK.
- Name the .pst file, or click OK to accept the default name.
- Click OK.
- Click Close.
- Click Folder List at the bottom of the navigation pane.
- In the navigation pane, you will now see your new .pst file that you named in step 5.
- Drag the .pst file information from your existing Outlook 2007 or Outlook 2003 folders to the new .pst file that you created.
Note If you have e-mail messages or other items that contain Unicode characters, they do not appear in the new .pst file that you created.
You can now use the .pst file that you created in the earlier versions of Outlook.