How to Convert an Exchange .OST File to a Pop3 .PST

I. Use your Local Offline Cached .OST file

If you are currently using use Exchange in Cached mode, you can simply choose to use Exchange "offline", and your local .OST file will remain, then simply add your Pop3 Account to Outlook.

II. Convert .OST to .PST

You can also totally migrate off Exchange keeping your emails, contacts, etc performing the following steps:

1.  Verify that the local computer is disconnected from the network (whether you dial in and/or connect up to the computer, do not connect until you are done with this step).
2.  Double-click on the Outlook icon located on your desktop.
3.  When prompted, select "Work Offline"
4.  Select File, and then Import and Export
5.  The Import and Export Wizard then guides you through the process.
6.  Select the Export to a file option
7.  From the Export to a file dialog, select Personal Folder File (.pst) and click Next
8.  Highlight the top level folder that you wish to export, and check the Include subfolders option, click next
9.  The default file is labeled backup.pst and the default location for this file is c:\documents and settings\%username%\local settings\application data\Microsoft\Outlook, change it if you need to.  Select ok
10. Leave the default options which should be Replace duplicates with items exported and then click finish.
11. Click OK to go back to the summary page, and do not change any encryption or password settings.

Log back into the network whether it's dialing up or reconnecting the network jack to your system.

Import the Mail Item:

1.  Click on the Outlook icon on your desktop and connect to the Exchange server when prompted
2.  Select from the File menu, Import and Export
3.  Follow the wizard like you did before, but this time you'll be selecting the Import from another program or file and click Next
4.  Select Personal Folder File (.pst) and then click Next
5.  Select the location of where you stored the exported file, unless you used the default location which is c:\documents and settings\%username%\local settings\application data\Microsoft\Outlook.
6.  Leave all the default options and click Next
7.  Leave the default items selected and verify that the items are being imported into the users mailbox.
8.  Click finish when done.  The items will now appear in the user's mailbox.