Repairing Corrupted PST File 


This technical note discusses how to repair PSTs before upload of files to a case in the Lexbe eDiscovery Platform (LEP), including how to handle possible data corruption issues in these file types.

What are PST Files

PST (abbreviation for Personal Storage Table) is a Microsoft proprietary file format used to store copies of email messages (MSGs), calendar events, and other items for use in Microsoft Outlook and Exchange. A related Microsoft file format is OST (abbreviation for Offline Storage Table). The PST file format is widely used as a delivery format (sometimes after conversion) in eDiscovery, even if email was originally stored in another format.

How Does LEP Process PSTs

Individual MSG email files are extracted from an uploaded PST, and attachments are in turn extracted from MSGs.  Metadata is extracted from the emails, including Date Sent, Sender, CCs, BCCs, etc.  The sent date is also assigned to the Master Date field for emails and attachments.  The email body and attachments are also converted to PDF for viewing when possible.  Note that an MSG file carries the date sent in Universal Time, and we use the time zone offset in the upload batch to set the appropriate Custodian time zone.

What Causes PST Corruption?

There are a number of factors that will corrupt or damage Outlook PST files such as, sudden shutdown of the program without data being saved due to system crash, exceeding the maximum file size of some versions (2 GBs), virus infection, Outlook program being defective or even upgrading to a newer Windows version can result in corruption. For these reasons, PSTs often need repair prior to upload to avoid data corruption issues.

How To Repair A PST File Before Uploading to LEP

Here are some troubleshooting and repair options to explore before uploading PST files:

1- Run Microsoft's inbox repair tool called ScanPST. Follow the instructions in How to Repair Outlook Personal Folder File (.pst). Often repairing a PST will allow it to run. ScanPST may change the MSG count as part of the repair so a backup of the original should be made before repair and QC procedures undertaken to account for any count discrepancies. Sometimes ScanPST may to be run several times before the utility reports that no further repairs are needed.

2- Install a third party PST Email Extractor. If ScanPST fails to repair the file, then there are some third party utilities available for purchase that will extract PSTs to MSGs. We recommend Aid4Mail, which is a standard in the eDiscovery industry. It may also be possible to extract MSGs from PSTs using Outlook itself or other utilities.

3- Recapture Non-Corrupt PSTs. The user may also consider requesting recapture of the subject PSTs if that is possible. 

4- Professional Services. Professional Services is available to assist in repairing PST files (billable hourly).

Repairing PSTs Best Practices

For quality control purposes, we recommend the user follow the steps below:

1- Back up a PST file before running the Inbox Repair tool.

2- Count the number of emails in the PST file before and after running the repair tool. If the number reduces there may be a problem that requires further investigation (technical work).

3- Run ScanPST on the repaired file again (after backing up) to determine there are no further errors.

Repairing MSG Files