Managing PST (Personal Storage Table) files in Microsoft Outlook is crucial for users who deal with extensive emails and attachments. By default, the maximum size of a PST file is limited to 47.5 GB, but in certain cases, you may need to increase this limit. Here’s a step-by-step guide to modify the PST file size limit using the Windows Registry Editor.

Step-by-Step Guide to Modify PST File Size Limit

1. Open the Registry Editor

   • Press Win + R to open the Run dialog box.
   • Type regedit and press Enter.
   • Click OK to proceed when prompted for administrative permissions.

2. Navigate to the PST Registry Key

   • In the Registry Editor, go to:
     HKEY_CURRENT_USER\Software\Microsoft\Office\<version_number>\Outlook\PST
   • Replace <version_number> with your version of Office (e.g., 16.0 for Office 2016).

3. Modify the MaxLargeFileSize Value

   • Select the PST key on the left panel.
   • On the right panel, locate and right-click MaxLargeFileSize.
   • Select Modify.

4. Set the Desired File Size Limit

   • Choose Decimal as the base.
   • Enter the desired size limit in megabytes (e.g., 51200 for 50 GB).
   • Click OK to save the changes.

5. Adjust the WarnLargeFileSize Value (Optional)

   • Similarly, modify the WarnLargeFileSize value to set a warning threshold for PST file size.
   • Ensure there is at least a 5% difference between MaxLargeFileSize and WarnLargeFileSize to avoid unexpected errors.

6. Restart Outlook

   • Close and reopen Microsoft Outlook for the changes to take effect.

Important Considerations

• Default Size: The default maximum PST file size is 47.5 GB (48,640 MB).
• Recommended Limit: Avoid setting limits beyond 100 GB to maintain system performance and file stability.
• Backup First: Always back up your registry before making changes to prevent potential issues.