Microsoft Outlook, the absolute leader in the segment of corporate desktop email clients, stores user data in OST and PST files. An OST file is a cached copy of the user’s mailbox stored on the MS Exchange server. A PST file is a personal folders file that contains the user’s email messages and is stored locally on the computer.

There are quite a number of Outlook users who faced, to some extent, problems opening .pst files because they were corrupted. The inability to open a user’s file with email messages is a real headache for administrators and help desks. In this article, we will focus on the main causes why personal folder files get corrupted and show you an easy way to restore them.

There are several causes of damage to personal folders storage files in Outlook: the damage can be due to file system errors (in this case, it is worth starting by checking the file system), and damaged structure of .pst files caused by an Outlook client crash (these happen quite often), power failure, virus attack, storing .pst files in a shared network folder (Microsoft does not support such settings), etc.

You should also remember the maximum .pst file size restriction in different versions of Outlook. If the maximum file size is exceeded or a large file is opened in an older version of the mail client, Outlook may work with errors. These are the .pst file size limits:

– Outlook 2002 and earlier versions – .pst files are in ANSI format and are limited to 2 GB.
– Outlook 2003 and Outlook 2007 – a 20 GB limit.
– Outlook 2010, Outlook 2013, and Outlook 2016 – .pst/.ost files are in Unicode format and are limited to a maximum size of 50 GB.

Also, you should keep in mind that the larger the file, the higher the chances of errors, and that is why the recommended personal folders file size is 2-8 GB.

The availability of such errors suggests that the .pst data file is corrupted and you need to recover its logical structure.

First of all, let’s find out where exactly Outlook stores its .pst files. By default, *.pst files (personal folders) and *.ost files (local cached copies of Exchange server folders) are stored in the following directories depending on your operating system version:

-Windows 2000, 2003, XP:
C:Documents and Settings%username%Local SettingsApplication DataMicrosoftOutlook.

– Windows Vista, Windows 7, Windows 8 and Windows 10:
C:users%username%AppDataLocalMicrosoftOutlook.

However, a user can create/move a personal folders file to another location, if necessary.

Important note! Before you start to recover a .pst file, make sure you have made a backup; by doing so, you will prevent possible further damage to the file that can be caused by a recovery utility or by Outlook.

To recover Outlook archive folders after they have been damaged, Microsoft has included a special utility Microsoft Outlook Inbox Repair Tool (scanpst.exe) in the Office suite. This little utility is not a panacea solution for recovering a Personal Folders file after any kind of corruption, but it can help solve typical problems with Personal Folders files.

You can find this utility in the directory: C:Program FilesMicrosoft OfficeOFFICE {MS Office version number, – 11,12,13,14}.

For example, here is the path to the directory that contains the scanpst.exe utility for Office 2016: C:Program FilesMicrosoft OfficeOFFICE16.

Let’s try to recover damaged items in a .pst file in automatic mode. To do so, we need to run the scanpst.exe utility and specify the path to the .pst file.

Important note! Before starting the utility, be sure to close Outlook and other processes that may use the Personal Folders file to recover.

Press Start to begin scanning the file for errors.

The file structure analysis and verification process consists of 8 stages. The time required for the check depends on the size of the file and the number of errors it may contain.

In our case, the utility reports that the personal folders file contains errors and suggests starting the recovery procedure (Repair button). If you have not created a backup copy of the .pst file, you can do so now by clicking the check box and specifying the file name.

After clicking Repair, the process of restoring a .pst starts; It also consists of 8 stages. In our example, it takes about 15 minutes to restore a 1 Gbyte file.

If all goes well, a repair complete message appears when the utility finishes its work, and then you can try to open a .pst file in Outlook.

So, as we have said before, the scanpst.exe utility should help you in most of the cases (around 90%) when you encounter errors or corrupt personal folder .pst files. However, this utility cannot help you if:

– the header of a file is damaged;
– the personal folders file is protected with a password;
– you need to restore accidentally deleted emails or folders;
– the maximum size of the .pst file is exceeded;
– the logical and physical structure of a personal folders file is badly damaged.

Accidentally deleted messages and folders can be restored from OST file.