Are you getting the following error when opening attachments from Windows Mail in Windows Vista, or Outlook Express in Windows XP?

(This is not a "fix-it" article, but it gives some useful information on how to deal with problems opening email attachments. Because the issue is related to file type associations, there is not a "single-fix" which resolves the problem for all file types. I’m writing this article as this is one of the Top FAQs in Windows.)

The error occurs if the file type is not registered, and/or the application that’s needed to open the file type is not installed in your PC. First, try saving the file locally and then open it. If you receive the same error, you’ll need to check if you have the corresponding application installed in your system to open the file type.

Fig 1: Mail client shows the file extension of the attachment.

If you don’t know which application opens the said file type, simply ask the sender on how to open the attachment. Other than that, you may check the file types list at Webopedia or query file type information at Filext.com to know which application opens the said file type.

In the event that the application is already installed in your system and yet the problem occurs, you should be able to fix this by associating the file type with the program. If you’re using Windows XP, see How to change which program starts when you double-click a file in Windows XP. For Windows Vista, see Windows Vista Help: Change which programs Windows uses by default.

RECOMMENDED READING

See section Identifying Attachment File Types and Setting File Associations in Decoding Internet Attachments - A Tutorial by MS-MVP Michael Santovec.

FIXES

Here are some pages which address the problem for certain file formats.

• Unable to open .DOC attachments from Windows Mail
• Unable to open .PDF attachments from Windows Mail
• Unable to open .PPS attachments from Windows Mail
• Unable to open .PPS attachments from Outlook Express

VIEW FILE ASSOCIATION DATA

FileExtInfo tool presents a list box containing all the file extensions registered in the system. To view the association information about a particular file type, choose the appropriate extension in the list box, and then click View file association report. This report can be vital for troubleshooting purposes. Personally, I’ve resolved hundreds of cases for my clients, using my own FileExtInfo tool.

Are you experiencing a file association related problem? You may post it in the Comments box below, or send it via the Feedback form.