Whenever I attempt to open an attachment within Outlook Express a message appears saying “C:\Documents and Settings\ken\Local Settings\Temporary Internet Files\Content.IE5\A1QEDO1T\. This file does not have a program associated with it for performing this action. Create an association in the Folder Options Control Panel”. The computer is running Windows XP.

Before we launch into an in-depth analysis of your problem, it is worthwhile to consider the process which Outlook Express performs when opening emails and attachments. When you open an email in Outlook Express, a new temporary file (with the file extension *.tmp) will be created within the Temporary Internet Files folder on your computer. This temporary file is the email you are reading, and is a method for Outlook Express to temporarily store the message being read. The name of the temporary file is randomly generated. Likewise, the name of the sub-folder which contains the temporary file (in the example above, A1QEDO1T) is also randomly generated.

The email attachment is contained (encapsulated) within the email itself. As such, if there is an attachment on an email message, that attachment is contained within the temporary (tmp) file which Outlook Express creates when you read the message. When you open the attachment, Outlook Express extracts the attached file from the email and places the file within the same temporary folder as the temporary email file. This is why when you attempt to open the attachment a message appears quoting the location of the attachment, as the temporary path which contains the tmp file of the email message which contains the attachment. Then, the program associated with the file type of the attachment will be called upon to open the file. For example, if the attachment is a PDF file (and you have Adobe Reader installed) Adobe Reader will be called upon to open the PDF file, just like double-clicking to open any other file on your computer. For reference, the attachment file and the temporary (tmp) email file should both remain in the temporary directory until you close Outlook Express.

In order to troubleshoot this problem, we need to take a look at the attachment file which is refusing to open. You say that this problem occurs “whenever I attempt to open an attachment within Outlook Express”. In actual fact, the problem may only be caused by a particular file type (e.g. PDF files, DOC files) but all the email attachments you have attempted to open are the same file type, leading you to believe that it is a problem affecting all attachments. Take a close look within Outlook Express at the attachments which are not opening to see whether you can narrow this down to one or two file types.

Once you have found the file type(s) causing the problem we can commence troubleshooting. Open one of the emails with an affected attachment and attempt to open the attachment. This should fail, but will extract the attachment into the temporary folder (which is what we need to happen). In the message that appears when you attempt to open the attachment note down the location of the attachment. Now navigate to the temporary folder and have a look at the attachment file. Open Windows Explorer or My Computer. To begin, we need to enable the display of hidden files and folders, so we can see the temporary folder. Go to the “Tools” menu > “Folder Options” > “View” tab and enable “Show hidden files and folders”. Click OK to save and close. Go to the “Start” menu > “Run” and type C:\Documents and Settings\\Local Settings\Temporary Internet Files\Content.IE5” and click OK (replacing YOUR USER NAME with your Windows user name). Once in this folder, you will see all the temporary folders. Open the temporary folder as noted in the Outlook Express message. Within that folder you should see the attachment.

The first thing you should try is double-click on the file to see whether it will open. If the application used to view the file does open (e.g. Adobe Reader) but does not open the file itself, this may indicate that the program does not like opening the file due to the rather long path name to that file (i.e. as the file is being opened from a temporary folder with a long file path). In this case, there is not much you can do except try to find an updated copy of the software which does support long path names. Alternatively, instead of attempting to open the attachment using Outlook Express you could save the file to a simple location (e.g. the desktop) and then manually open the file from that location.

In the situation where the file does not open when double-clicked this indicates that the file association has become lost and needs to be fixed. Right-click on the file and select “Open With” (and “Choose Program” if asked). In the window that appears, select the program you wish to use to open the file. Tick the box “Always use the selected program to open this kind of file” and click OK. The file should now open and the file association should also be reinstated. When you attempt to open an attachment from within Outlook Express this should also now work.

However, you may find yourself in the situation where the file opens perfectly fine when double-clicked in the temporary folder, without any additional changes required. In this situation the file association is still the most likely culprit and you should follow the instructions provided in the previous point to reset and re-establish the association between the file type being opened and the application.