You can try "Move to folders" feature of MS Outlook 2003 to split PST file into multiple parts. This may take a lot of time and technical understanding. Follow the steps given below: 1. Launch MS Outlook. 2. Click File tab > New > Outlook Data File. 3. A dialog box “New Outlook Data File” will appear. Select Office Outlook Personal Folder File (.pst) and click OK. 4. A new dialog box “Create Microsoft Personal Folders” will pop up. Type a display name for this new PST file. 5. Now select the folder that you want to move to the new PST file. You may move one or more items to new PST file. 6. On the Edit menu, click Move to Folder. 7. A new dialog box “Move Items” will appear. Click New. 8. Again a new dialog box “Create New Folder” will appear. Enter a new name for this new folder in the Name box. 9. Click the new PST file under the “Select where to place the folder” option. Then click OK. 10. In the “Move Items” dialog box, make sure that the new folder in the new PST file is selected. Click OK. You can also try a third-party tool. I can recommend SysInfoTools PST Split tool here to split PST files into multiple parts. It will safely split a large sized PST file (ANSI and Unicode) without causing any changes to the original files. Thanks.