Thousands of people depend upon Microsoft Outlook for their email messages, keeping track of contact information, organizing their calendars, and more. For many of them this software will work just fine, day after day, year after year. Until that one, horrifying day when instead of launching properly, Outlook instead displays an obscure error message. That’s the day many of us first learn about PST files.
Whether we’re talking about Outlook 2003, XP, Vista, or even the newest version, Outlook 2010, every version of this program from the very beginning stores all of its information in a single file, commonly called a Personal Folders File. This file resides on your local hard drive, is often named Outlook.pst, and is used to store every piece of email you receive, every calendar item you create, every task you schedule, note you take, etc. (Inbox, Calendar, and Contacts.) Whether you get your email using a POP3, IMAP, or HTPP (Microsoft Windows Live Hotmail) account doesn’t matter. Once Outlook retrieves your mail it needs somewhere local to store it and that’s what the PST file is for.
As you can imagine, the longer you use Outlook, and the more email and other information you accumulate, the bigger your outlook.pst file will grow. In some ways this is a good thing as it reduces the burden on email servers, such as the ones supplied by your Internet Service Provider (ISP), which often impose limits on how much you can store. But in other ways this isn’t so good as Outlook’s very own storage file can grow without bounds and end up having issues.
PST File Corruption
In fact, early versions had a problem if the .pst file grew larger than 2 GB. Once that happened, Outlook could no longer open the file and there was a good chance you would have to truncate the file (using Microsoft’s PST2GB tool) and lose some of your data. Then, beginning with Microsoft Office Outlook 2003, the PST data file format was modified to no longer have a fixed size limit (although it defaults to a maximum size of 20 GB), and to work better with multilingual Unicode data (essentially, foreign language content).
While this new file format is an improvement, Outlook still suffers from the fact that as a PST file is essentially a binary database format, rather than a simple text file, it is prone to corruption damage that can render the file unreadable. (For example, attempting to read the file over a network connection is specifically unsupported by Microsoft and known to corrupt pst files.) When that happens, you will either see error messages and/or Outlook will no longer be able to open the Outlook.pst file. And you’ll have to repair the damage using scanpst.exe or a third party utility.
It goes without saying that any file that is this important should be backed up regularly. Unfortunately, many users of Outlook do not have a recent backup of their personal folders file. If that’s the case, do not panic. Reacting in haste will only make things worse. If you suspect your Outlook.pst file is corrupt, or Outlook is reporting an error, the first thing you should do is exit the application. Then, you should locate the Outlook.pst file on your local hard drive and make a backup copy of it, either on the same drive, a flash drive, a writeable CD ROM, or a backup drive. If any of the subsequent steps should fail, you can always restore your backup and be no worse than where you are now.
How To Repair PST Files
When you suspect corruption of your Outlook PST file, you should back it up, then run scanpst.exe, the free Inbox Repair Tool from Microsoft. Unfortunately, this utility is rather weak in what kinds of errors it is able to repair, and how much data it is able to recover. But since it is free it is still the best place to start. Don’t download scanpst.exe from the Internet as it comes with Microsoft Office and needs to match the version of Office you have installed on your computer. Simply search your computer for “scanpst.exe” and you should be able to find it.
If the Inbox Repair Tool was unable to fix all the damage or resulted in a loss of your valuable data, then your next step is to find a third-party utility that can do a better job on your particular file. Unfortunately, there simply are no free tools on the market. The job of recovering data from corrupt files is extremely challenging and all the available tools have a price, although most do have a free download or trial version that will give you an idea of whether or not they will work for you. Here are a few that are worth evaluating:
- The Stellar Phoenix company has a great deal of experience in data recovery in general. They make a Stellar Outlook PST Repair program that you can download and evaluate. Stellar Phoenix Outlook includes a file splitting utility and a password recovery feature as part of their offering.
- Data Numen has also been around a while and makes a variety of data recovery products, including their Advanced Outlook Repair (AOR) tool. This appears to be the most expensive option, so be sure to read about it and download the free demo.
- Nucleus Data Recovery is another established vendor in the data recovery market. They are the creators of the Kernel for Outlook PST Repair Tool, which you can also download and try on your own. Kernel is available in three different licenses, depending on how many files you need to repair and whether or not you are in a corporate environment.
- The Disk Doctors have a tool called the Outlook Mail Recovery Program
with a downloadable demo. However, they don’t appear to offer any refunds, so make sure you evaluate this one fully.
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