In an effort to protect users from potential email problems like viruses, malicious scripts, etc., Microsoft blocked 43 file types from being opened or executed beginning with Outlook 2002. With the release of Outlook 2003 that number rose to 51. While this can be a good idea there may be occasions when we want an attachment such as one a friend may have sent. That's where Outlook Attachments can help. Operation is very simple. If you receive an attachment that is blocked close Outlook, use Outlook Attachments to highlight and allow the file type, reopen Outlook and the file will now be available.