Personal Folders (PST) and Offline Folders (OST) file problems

Topic T1120 Applies to All NEO products


Personal Folders (PST) files and Offline Folders (OST) files are susceptible to corruptions. If a corruption occurs in a PST or an OST, NEO may report errors associated with MAPI calls to Outlook for message transport, editing or other functions. If problems such as this occur in a PST file or an OST file, you may need to scan them for errors and corruptions. The utility to scan PST and OST files is called the Inbox Repair Tool - 'SCANPST.EXE'.

The Inbox Repair Tool may be used to resolve corruption issues for both 'Outlook 97-2002 Personal Folders Files (.pst)' and 'Office Outlook Personal Folders File (.pst)' (Unicode) forms of PST files as well as for OST files. The Inbox Repair Tool is used to make sure that the physical structure of the PST or OST file is intact and can diagnose and repair errors if found in the files. It will reset the PST or OST file structure and rebuild headers.

For OST files, the Inbox Repair Tool will not scan your mailbox on the Microsoft Exchange Server, it only deals with the physical OST file structure. In the event of synchronization problems between the Exchange Server and an OST file, there is a separate utility to analyze this called the OST Integrity Check Tool - 'SCANOST.EXE'. Problems you may encounter are: some items are missing from your OST file; or from your mailbox after you synchronize your OST file and mailbox. ('Items' here include e-mail messages, appointments, contacts, tasks, journal entries, notes, posted items, and documents.) If these synchronization problems occur or you have other problems synchronizing between the Exchange Server mailbox and your OST file, you should use the OST Integrity Check Tool

Resolutions for a Corrupt PST or OST File

You will need to locate a utility on your PC named 'SCANPST.EXE', the Microsoft Outlook Inbox Repair Tool. You can find it using your Windows Explorer Search, or alternatively, see the appropriate Microsoft Knowledge Base article below for your version and installation of Outlook:

Several other articles are available in the Microsoft Knowledge Base related to the Inbox Repair Tool.

If you are unsure of the physical location of the PST that you are trying to repair, you can locate it by using Windows Explorer Search and searching on '*.PST'. Once you know its location, you may browse to it via the Inbox Repair Utility. Please note that for large message stores, SCANPST is pretty slow.

Resolutions for Synchronization Problems With an OST

There is a utility on your PC named 'SCANOST.EXE', the Microsoft Outlook OST Integrity Checker. You can find it using your Windows Explorer Search, or alternatively, there are a number of Microsoft Knowledge Base and Microsoft Office Assistance articles that describe the tool and explain the use of the tool for your version and installation of Outlook (for example Outlook 2000 C&W). There are additional articles that cover other issues surrounding the OST Integrity Check Tool and it's use.

In short, the OST Integrity Check Tool scans your OST file and your Exchange Server mailbox and compares items and folders in the two and attempts to reconcile synchronization differences between the mailbox and your local OST file. The OST Integrity Check Tool does not change your Exchange Server mailbox. "The tool records any differences it discovers between the mailbox and the local OST file in a scan log so that you can see what discrepancies it found and resolved. The scan log also identifies any situations the tool couldn't correct that you will need to fix manually. The scan log can be found in your Deleted Items folder." (from a Microsoft Office Assistance article)

Additional Crisis Management Information

In rare cases where a PST is severely corrupt, or is an 'Outlook 97-2002 Personal Folders File (.pst)' that is beyond the 2.0Gb mark and in either case is inaccessible using Outlook, a third-party product is available for recovering your PST files. You can find it at Be prepared, the price tag may sting just a little.

Last updated: 07 Feb 2005