Every now and then you might receive an email with an attachment that has a file type your computer may not recognise. All files have what is called a MIME type. This means, when you open the file your Windows PC knows which installed application to use to open the file.
For example, someone sends you an email with a .PDF attachment. You download the attachment to your Desktop, double-click and Adobe Reador or any other PDF reading application will open the attachment and display the contents in that application.
So, what do you do when you get an email attachment that is not recognised by your PC?
If you want to edit your file type associations, use the following steps:
From there you can update, change or simply attach an application to one of the many file types offered for configuration by Windows.
Sometimes you might have one or more applications installed on your PC that is capable of opening a file and recognising it's MIME type. Choose whichever is your most common and in future when you double-click on a file, it will be opened by whichever application you chose.