Command Center

Understanding Outlook Express Files

Sound prevention begins with sound understanding, so let's begin with a look at the Outlook Express user files. Each folder that you see in the Outlook Express Folder list is stored on your hard disk as a single file with the same name as the folder but with the extension DBX added at the end, such as "Inbox.dbx" and "Sent Items.dbx". All these DBX files are stored in a single Windows folder called, not surprisingly, the Store Folder. The Store Folder is usually located deep within the Documents and Settings folder in Windows 2000 and Windows XP, and is by default marked as a hidden folder. This makes it tricky to find your Store Folder in Windows Explorer, but there is a very good reason for this. One source of DBX corruption is trying to open and edit a DBX file yourself.

Tip: Avoid the temptation of clicking on a DBX file to see what it contains.

It is enough to know that a message inside a DBX is not simply a string of text that you can read, but rather is broken up into parts which are not assembled into a legible message until you access the corresponding folder in Outlook Express. Also know that altering even a single byte in a DBX file might render the file completely unusable by Outlook Express.

Finding Your Store Folder

Here is a quick and easy way to display your Store Folder with just a few clicks and keystrokes.

Click the Store Folder button to see the path to your Outlook Express DBX files.

Signs and Symptoms of DBX Corruption

The first symptoms of DBX corruption usually begin innocently enough. You might notice that Outlook Express feels sluggish when starting, or when switching folders. Simple tasks like marking a message as read might take several seconds. Such performance issues usually mean that some minor corruption has occurred but has not yet reached a critical level. If the corruption is more extensive but involves a single e-mail or news folder, Outlook Express might crash with this error when you try to open the damaged folder:

In these cases the corruption can usually be repaired by compacting all your Outlook Express folders. To minimize the chance of errors during the compaction process, I recommend this simple procedure:

If compacting does not correct the corruption, you will need to move all messages out of the damaged folder (if possible), close Outlook Express, and then delete the associated DBX file for that folder. If you cannot open the folder, move the damaged DBX file out of the Store Folder into a new folder you create. I will explain later how you can recover most messages from the corrupt file.

In cases of severe corruption Outlook Express will no longer recognize that the DBX file exits, and so the corresponding folder will disappear from the Folder list. If however the corrupt file is Inbox.dbx, Outlook Express will sometimes create a new one and append a number to its name, such as Inbox(1).dbx. If this happens when you open the Inbox, you will see your Inbox messages disappear right before your very eyes!

When Special Folders Stop Being Special

When a special folder becomes corrupt, the first sign is usually just that the folder stops working. For example, you might find that messages you send are no longer being saved in the Sent Items folder or that you are suddenly unable to delete messages, or you cannot open messages in the Drafts folder. If the Inbox is corrupt you will usually see just an empty folder, although sometimes new e-mail will not be downloaded. In the case of the Sent Items or Outbox folders, Outlook Express might crash when you attempt to send a message, presenting this error:

If the Inbox is corrupt, Outlook Express might not start, but in most cases it will do so by creating a new DBX file named Inbox(1).dbx.

In all these cases compacting all folders often fixes the damage. If it fails to do so, you will need a new DBX file for the damaged folder.

The Show-Stopper: Folders.dbx

In the case of one important file, corruption can cause Outlook Express not only to crash but also to be completely unable to start, presenting just the "working" hour-glass cursor or one or more of the following error messages:

In these cases the corruption is probably in the file "Folders.dbx". This is the master index of the entire Store Folder and without it, Outlook Express cannot do anything. Should you find yourself in this situation, the only solution is to delete the corrupt file from the Store Folder. That will allow Outlook Express to start and to build a new "Folders.dbx" by re-indexing all DBX files it finds in the Store Folder. This is not without consequences however, and so is not something to do unless absolutely necessary. You will have to do some work to replace the information lost, namely:

Removing a single byte from a single DBX file can have dire results.

Compact All Folders vs. Compact Folder

You can always compact a single folder by pointing to Folder on the File menu, and then clicking Compact. This is recommended every time you make large changes to any folder. But in order to compact "Folders.dbx", the crucial index of the Store Folder, you must instead click Compact All Folders. Outlook Express will first compact all your e-mail and news folders, and will finish by compacting "Folders.dbx".

Viral Irony: The Most Common Cause of Corruption

When encountering the symptoms of DBX corruption, many people immediately fear that their computer is infected with a virus. As surprising and ironic as it may seem though, the most common cause of DBX corruption is not a virus, but rather anti-virus programs that are configured to scan incoming or outgoing e-mail. Even the most well-known anti-virus programs have exhibited this problem from time to time. To lessen the risk of such corruption you should disable the e-mail scanning module in your anti-virus program. This is usually easy to do by looking at the user-configurable options in the anti-virus program. It is not at all necessary to scan e-mail for viruses to protect your computer.

Now before you dismiss me as mad, let me explain why e-mail scanning is unnecessary. Almost every anti-virus program for Windows installs by default a system scan that runs in the background every time Windows starts. This scan is necessary to protect your computer. If you receive a virus in an e-mail attachment, the virus cannot do anything at all until you actually open the attachment. At that time Outlook Express extracts the attachment from the message and saves it to the Temporary Internet Files folder on your hard disk and attempts to open the file. And it is precisely at that moment that a background system scan will detect the virus, provided it is able to do so, and stop the virus from executing. The system scan will usually delete the infected file from the Temporary Internet Files folder, or else move it to quarantine. To remove the infected e-mail message in Outlook Express, simply hold the Shift key while you press the Delete key. That's all it takes to keep your computer safe, both from e-mail viruses and e-mail anti-virus scanners. Scanning e-mail as it arrives therefore adds nothing to your level of protection. It might indeed make you feel more protected, but that feeling is an illusion. If the system scan is unable to detect the virus, the e-mail scan will fail to do so also.

When the Cure Kills: Compacting and Corruption

As stated earlier, compacting all folders in Outlook Express frequently repairs mild corruption. But surprisingly enough, and again as ironic as it seems, the compaction process itself has also been implicated in causing corruption. Before Windows XP Service Pack 2 (SP2), Outlook Express was configured by default to compact files automatically after Outlook Express had been inactive for some minutes. However, although Outlook Express might have been inactive, the same could not always be said for other programs being used when compaction began. On some systems, particularly those with limited amounts of RAM or slow processors, the sudden drain on computer resources sometimes caused the compaction process to hiccough, and all too often a damaged DBX was the result.

It is largely for this reason that the background compaction feature has been removed in Windows XP SP2. Now Outlook Express will compact automatically only after you have opened and closed Outlook Express 100 times. It will do so not in the background, when you might be busy doing other things on the computer, but rather when you close Outlook Express for that 100th time. Do not cancel this compaction, nor use your computer until it is finished. For best results however, you should still compact all folders on a regular basis, such as weekly or bi-weekly.

If you have not installed Windows XP SP2, you should disable the background compaction to lessen the chance of it damaging your files. To do so:

Minimizing the Risk Is Also Minimizing the Loss

"Don't put all your eggs in one basket," goes the old saying. In Outlook Express this translates into "don't save all your messages in one folder, especially not the Inbox." By keeping your DBX files small, you minimize the risk of corruption while at the same time minimizing the loss should corruption occur. This is especially true for the Inbox since it is the folder that changes the most. So keep your Inbox lean and healthy by using it for what it is, a box for incoming messages waiting to be stored or deleted, and not as a place to store all the e-mail you've ever received. Not only will Outlook Express be less likely to lose your e-mail, it will also perform more efficiently.

Don't Forget Sent Items

Most of us don't look in this folder very regularly, yet it grows every time you send a message. It is therefore very easy for the "Sent Items.dbx" file to grow very large. Be sure to move messages out of Sent Items and into sub-folders from time to time to lessen the risk of corruption. A good rule of thumb is to keep no more than 2,000 or so messages in Sent Items.

Recovering from Corruption

In the event one of your mail folder's DBX file suffers from corruption that is not cured by compacting all folders, there is hope for recovering the messages it contains.

Ten Steps of Prevention

If you follow the ten stops outlined here, you will greatly reduce the chances that your DBX files will become corrupt.

These simple steps will help keep your Outlook Express working in tiptop shape so that hopefully you will never need that emergency copy of DBXtract.

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